JP5098791B2 - Coating apparatus, coating method, and storage medium - Google Patents

Description

  The present invention relates to a coating apparatus, a coating method, and a storage medium for coating a substrate with a coating solution such as a resist solution.

  In the manufacturing process of semiconductor devices and LCDs, a resist pattern is formed on a substrate by photolithography. In these processes, a resist solution is applied to a substrate such as a semiconductor wafer (hereinafter referred to as “wafer”) or a glass substrate for a liquid crystal display to form a thin resist film, and then the resist film is exposed and then developed. Is performed in a series of steps to obtain a desired pattern.

  By the way, a spin coating method (spin coating method) is widely used as a technique for applying a coating solution containing a coating film component and a solvent, such as a resist solution, to the substrate. In this method, a wafer is first placed on a spin chuck and held substantially horizontally, and a resist is applied to the central portion of the wafer from a nozzle provided on the upper side of the wafer while rotating the wafer around a vertical axis. Supply. The resist solution dropped on the wafer is extended from the central portion of the wafer toward the outer peripheral portion by centrifugal force, and then the number of rotations of the wafer is reduced to level the resist solution. After this leveling, the number of rotations of the wafer is increased again, and excess resist solution on the wafer is shaken off and removed. On the other hand, the solvent contained in the resist solution on the wafer is volatilized by being exposed to the airflow generated on the wafer by the rotation of the wafer. Thus, the drying of the resist solution is promoted by the rotation of the wafer, and a resist film is formed.

  In such a coating method, the film thickness of the coating film to be formed becomes thinner as the number of rotations of the wafer is increased. Therefore, the film thickness of the coating film can be controlled by adjusting the number of rotations. However, when the number of rotations is increased to a certain value or more as the size of the wafer increases, for example, about 30 wrinkled films are formed on the surface of the resist film along the circumferential direction in a region near the periphery of the wafer. Sites with non-uniform thickness may be formed. This wrinkle is called a wind cut mark, and the part where it is formed cannot be used as a device region. Therefore, when a coating solution having the same composition is used, the lower limit value of the film thickness is limited. There is a problem that the control range of the film thickness by one coating liquid is narrow.

  At this time, when the film thickness is made smaller than the lower limit, it can be dealt with by reducing the concentration (viscosity) of the coating solution. Accordingly, in order to increase the film thickness control range, it is only necessary to prepare a number of coating liquid supply systems having different concentrations corresponding to the film thickness control range. However, in such a configuration, the apparatus configuration becomes complicated. There is a problem that the apparatus becomes larger.

  Here, the wind-off mark is formed by exposing the resist solution to a non-uniform air flow formed on the wafer surface as the wafer rotates during the process of volatilization of the solvent in the resist solution. In order to suppress the generation of a non-uniform airflow on the wafer surface, the present inventors provide a cover that can be rotated together with the wafer around the wafer placed on the spin chuck. We are investigating a method of forming an enclosed space and applying a resist solution in this space.

  When the resist solution is applied by this method, it is recognized that the control range of the film thickness can be expanded in the direction of the thin film, as shown in examples described later. However, the solvent in the resist solution is less likely to volatilize within the enclosed space, and the solvent is not completely removed by rotating the wafer for about 60 seconds as in the conventional case. For this reason, it waits for the said solvent to dry naturally, but when it is naturally dried in this way, there exists a problem that film | membrane nonuniformity will generate | occur | produce easily. This unevenness of the film means a local film thickness difference caused by spontaneous volatilization of the solvent in the resist film.

  By the way, Patent Document 1 discloses a rotary coating apparatus provided with a rotary table that rotates while holding a substrate, and an upper rotary plate that is provided above the substrate on the rotary table so as to face the substrate. Has been proposed. In this apparatus, while rotating the rotating table and the upper rotating plate, a coating process is performed on the substrate. After the coating process is finished, the rotation of the rotating table and the upper rotating plate is temporarily stopped, and then the rotation of the substrate is resumed. On the other hand, the upper rotating plate is raised without rotating. However, in this configuration, since the upper rotating plate is raised without rotating, the airflow on the substrate tends to be disturbed. For this reason, as a result, when the solvent in the coating film volatilizes, it is affected by the turbulence of the air flow, and it is impossible to suppress the occurrence of wind-cut marks, and the problem of the present invention cannot be solved.

Japanese Patent Laid-Open No. 11-74173 (FIG. 1, paragraph 0006)

  The present invention has been made under such circumstances, and its purpose is to suppress the occurrence of wind-off marks with one type of coating liquid when applying the coating liquid in a state where the substrate is rotated, An object of the present invention is to provide a technique capable of increasing the adjustment range of the thickness of the coating film.

  For this reason, the coating apparatus of the present invention holds the substrate substantially horizontally and faces the substrate with a substrate holding part rotating around the vertical axis and a gap above the substrate held by the substrate holding part. A cover member that is larger than the substrate, is provided so as to be rotatable about a vertical axis, a lifting mechanism that moves the cover member up and down relatively with respect to the substrate holding portion, and the substrate holding portion. A coating liquid nozzle for supplying a coating liquid containing a coating film component and a solvent to the held substrate surface, and a control unit for controlling the operation of the substrate holding unit, the cover member, and the lifting mechanism, The control unit moves the upper plate closer to the substrate surface and rotates the substrate holding unit and the cover member in the same direction, thereby centrifugally applying the coating liquid supplied to the center portion of the substrate surface. Extended by Adjusting the film thickness of the coating film, and then raising the cover member relative to the substrate holding portion while rotating the substrate holding portion and the cover member at a lower rotational speed than the step. And evaporating a solvent in the coating film.

  In this case, a fixing member including an annular member formed in an annular shape in the circumferential direction of the substrate via a gap on the back surface side of the substrate held by the substrate holding unit is provided, and the cover member is attached to the substrate. It is preferable to be configured to surround the substrate together with the fixing member when approaching. Further, the cover member may be configured to be rotatable by a rotation mechanism different from the substrate holding part. Furthermore, the coating liquid nozzle may be provided on the cover member.

  Furthermore, a first gas supply means for supplying a first gas having a lower viscosity than air is provided between the cover member and the substrate held by the substrate holding portion via the cover member, and the control The portion may be configured to output a control signal for supplying the first gas when the cover member is rotated at a rotation speed when adjusting the film thickness of the coating film. A second gas supply unit configured to supply a second gas different from the first gas between the cover member and the substrate held by the substrate holding unit via the cover member; May be configured to output a control signal for supplying a second gas instead of the first gas when the cover member is raised relative to the substrate holding portion. .

  Furthermore, a cup that covers the side and lower sides of the substrate held by the substrate holding part, an exhaust means for exhausting the atmosphere in the cup, and an atmosphere in the cup are adjusted to a predetermined pressure. An exhaust amount adjusting unit for adjusting the exhaust amount of the exhaust means, and when the control unit supplies gas through the cover member, the exhaust amount is increased, and the gas is supplied through the cover member. When not supplied, the control signal may be output so as to make the exhaust amount smaller than when supplying gas through the cover member.

The coating method of the present invention includes a step of holding the substrate substantially horizontally on the substrate holding portion, and a step of supplying a coating solution containing a component of the coating film and a solvent to the central portion of the substrate held on the substrate holding portion. , an upper plate facing the said substrate through a gap on the upper side of the substrate held by the substrate holding section, rotatably provided around a vertical axis, the larger the cover member than the substrate, the upper plate Is positioned close to the substrate surface, and then the substrate holding part and the cover member are rotated in the same direction to extend the coating solution on the substrate surface by centrifugal force, thereby reducing the film thickness of the coating film. And adjusting the cover member relative to the substrate holding portion while rotating the substrate holding portion and the cover member at a rotation speed lower than that in the step. Volatile solvent Characterized in that it comprises a step of, a.

  At this time, when the cover member is rotated at the rotation speed for adjusting the film thickness of the coating film, a first gas having a lower viscosity than air is supplied between the cover member and the substrate. Alternatively, when the cover member is raised relative to the substrate holding portion, the first gas is used instead of the first gas between the cover member and the substrate. A second gas different from that may be supplied.

Also comprising a cup for covering the lateral side and the lower side of the substrate held by the substrate holding unit, when supplying gas between the front Symbol cover member and the substrate are evacuated in greater displacement volume of the said cup, When the gas is not supplied between the cover member and the substrate, the pressure in the cup is adjusted by exhausting the inside of the cup with a smaller exhaust amount than when supplying the gas between the cover member and the substrate. It may be.

  Furthermore, the storage medium of the present invention is a coating apparatus that supplies the coating liquid to the center of the substrate held substantially horizontally by the substrate holding unit, and rotates the substrate holding unit to apply the coating liquid to the surface of the substrate. A storage medium storing a computer program to be used, wherein the program has a group of steps so as to execute the application method described above.

  According to the present invention, the step of adjusting the film thickness of the coating film by extending the coating solution supplied to the central portion of the substrate surface by centrifugal force lowers the cover member and brings the upper plate closer to the surface of the substrate. In this state, the cover member is rotated in the same direction as the substrate holding portion, so that the turbulence of the air current on the surface of the substrate can be suppressed, and the occurrence of wind-off marks can be suppressed even when the film thickness is reduced. Further, in the stage of volatilizing the solvent in the coating film, the substrate holding unit and the cover member are rotated at a lower rotational speed than when adjusting the film thickness of the coating film, and the cover member is moved to the substrate holding part. Therefore, it is possible to promote the volatilization of the solvent while suppressing the occurrence of turbulence of the airflow, and the film unevenness caused by the natural evaporation of the solvent remaining in the coating film. Can be suppressed. For these reasons, when obtaining a coating film having a uniform film thickness over a wide area, the film thickness range adjusted by one type of coating liquid can be widened.

  In the embodiments described below, a configuration in which the coating apparatus of the present invention is applied to a coating unit that performs a process of coating a substrate with a coating solution, such as a resist solution, will be described as an example. FIG. 1 shows a cross-sectional view of the coating unit. In the figure, reference numeral 2 denotes a spin chuck that forms a substrate holding portion for holding the wafer W horizontally by sucking and adsorbing a central portion on the back surface side of a semiconductor wafer W (hereinafter referred to as “wafer W”) forming a substrate. The spin chuck 2 is connected to a first elevating mechanism 22 and a motor M1 forming a first rotating mechanism via a shaft portion 21, and is configured to be rotatable and elevable around a vertical axis while holding the wafer W. Has been.

  In the figure, reference numeral 23 denotes a cup provided so as to surround the wafer W outside the side peripheral portion and the bottom portion of the wafer held by the spin chuck 2. The upper surface of the cup 23 is opened to a size larger than the wafer W in order to transfer the wafer W. On the bottom side of the cup 23, a liquid receiving portion 24 having a concave shape is provided over the entire periphery on the lower side of the periphery of the wafer W. The liquid receiving portion 24 is divided into an outer region and an inner region. A drain pipe 25 for discharging a drain of the stored resist solution is connected to the bottom of the outer region, and a valve is connected to the bottom of the inner region. V1 is connected to an exhaust means 28 via an exhaust path 26 having an exhaust damper 27 that forms an exhaust amount adjusting section.

  The spin chuck 2 is configured to be movable up and down between the processing position in the cup 23 and the transfer position on the upper side of the cup 23 by the first lifting mechanism 22. The position shown in FIG. 1 is a processing position, and the delivery position is a position where the wafer W is delivered between an external transfer means (not shown) and the spin chuck 2. Then, on the lower side of the wafer W arranged at the processing position in the cup 23, the planar shape is, for example, a circular shape so as to face the back surface of the wafer W and cover the back surface of the wafer W with a gap. The lower plate 31 is provided.

  The lower plate 31 has an outer edge located outside the outer edge of the wafer W, and an opening 31a that forms a moving region in which the shaft portion 21 of the spin chuck 2 moves up and down is formed at the center. The outer edge of the opening 31 a is formed, for example, on the lower side of the spin chuck 2. On the upper surface of the lower plate 31, a wall member 32 forming an annular member is erected at a position outside the outer edge of the wafer W. The wall member 32 is provided in an annular shape so as to surround the entire outer edge of the wafer W along the circumferential direction, for example, and the height thereof is set to be higher than the surface of the wafer W at the processing position, for example. Yes. Thus, in this example, the lower plate 31 and the wall member 32 constitute a fixing member.

  On the other hand, a cover member 4 is provided on the upper side of the wafer W held by the spin chuck 2 so as to cover the upper side and the side side of the wafer W through a gap. The cover member 4 includes an upper plate 41 having a planar shape, for example, a circular shape and larger than the wafer W so as to face the upper surface of the wafer W at the processing position. The upper plate 41 has an outer edge located outside the outer edge of the wafer W, and a central portion of the upper plate 41 is provided with a coating liquid supply region from a coating liquid nozzle 6 to be described later. For example, an opening 41a having a diameter of about 5 mm is formed.

  Further, the upper plate 41 includes a side wall portion 42 that extends downward at a position outside the outer edge of the wafer W. Here, the cover member 4 is configured to be movable up and down as will be described later, and when the cover member 4 is located at the application position shown in FIG. 1, for example, outside the wall member 32, The entire side portion of the wafer W is provided so as to surround the circumferential direction. When the cover member 4 is located at the coating position, the lower end of the side wall portion 42 is set to be located below the back surface of the wafer W at the processing position, for example.

  A cylindrical rotation holding portion 51 is provided at the center of the upper surface of the upper plate 41 in order to hold the upper plate 41 in a suspended state. The rotation holding part 51 has an arrangement area of the coating liquid nozzle 6 formed therein, and the upper end side thereof is closed except for an area opened to penetrate the coating liquid nozzle 6. And the upper surface of this rotation holding | maintenance part 51 is connected to the support plate 53 extended substantially horizontally via the cylindrical support member 52, for example.

  A timing belt 55 is wound around the rotation holding portion 51 and the rotation shaft 54 of the motor M2 that forms the second rotation mechanism, whereby the rotation holding portion 51 is configured to be rotatable around the vertical axis. ing. Further, the support plate 53 and the motor M2 are respectively connected to the lower surface of the elevating plate 56, and the cover member 4 can be moved up and down by elevating the elevating plate 56 by a second elevating mechanism 57. Is done.

  As described above, the cover member 4 is provided with a coating position where the upper plate 31 approaches the surface of the wafer W at the processing position, a drying position above the coating position, and a delivery position above the drying position. It is configured to be movable up and down between positions, and is configured to be rotatable around a vertical axis at the application position and the drying position. The position shown in FIG. 1 is a coating position, and the delivery position is a position above the spin chuck 2 at the delivery position, and the wafer W is placed between the spin chuck 2 and an external transfer means. It is a position when delivering.

  A coating liquid nozzle 6 for discharging a coating liquid, such as a resist liquid, to the wafer W at the processing position is provided at a substantially central portion of the support plate 53. The nozzle 6 is held by, for example, a cylindrical nozzle support portion 61 provided on the upper surface of the upper plate 41 such that the tip thereof is positioned above the lower surface of the upper plate 41 of the cover member 4, for example. ing. The other end side of the coating solution nozzle 6 includes a valve V2 and a flow rate control unit 62, and the resist solution is stored through a supply path 63 configured to be able to move flexibly in accordance with the raising and lowering and rotation of the cover member 4. The resist solution supply source 64 is connected.

  Here, an example of dimensions of each part will be described. When the spin chuck 2 is positioned at the processing position and the cover member 4 is positioned at the coating position, the wafer W is surrounded by the cover member 4 and the fixing member. In the enclosed state, the distance L1 between the wafer W and the lower surface of the cover member 4 is, for example, 2 mm to 10 mm, preferably about 3 mm, and the distance L2 between the upper surface of the lower plate 31 and the lower surface of the cover member 4 is, for example, 30 mm to 60 mm. The gap between the wall member 32 and the upper plate 41 is, for example, about 2 mm, the gap between the side wall portion 42 and the lower plate 31 is, for example, about 2 mm, and the gap between the lower plate 31 and the spin chuck 2 is, for example, It is about 2 mm, and the wall member 32 and the side wall portion 42 are positioned on the side of the wafer W. Therefore, at this position, when viewed from the wafer W, the back surface side of the wafer W is covered with the spin chuck 2 and the lower plate 31, the front surface side is covered with the upper plate 41, and the side surfaces are covered with the wall member 32 and the side wall portion 42, respectively. An enclosed space S1 is formed around the wafer W.

  When the spin chuck 2 is positioned at the processing position and the cover member 4 is positioned at the drying position, the distance L1 between the wafer W and the lower surface of the cover member 4 is, for example, about 3 mm to 15 mm, preferably about 7 mm. It is preferable to set, and as shown in FIG. 3A, the wall member 32 and the side wall portion 42 are separated from each other in the vertical direction. The reason why it is preferable to set the cover member 4 at this position is that if the distance L1 is too large, the airflow on the surface of the wafer W may be disturbed, and if it is too small, volatilization of the solvent in the resist film is difficult to promote. . At this position, when viewed from the wafer W, the distance from the upper plate 41 is large on the front side of the wafer W, and the wall member 32 and the side wall portion 42 do not overlap in the vertical direction also on the side. The space will be open.

  In the above, the first and second rotating mechanisms M1 and M2, the first and second elevating mechanisms 22 and 57, the valves V1 and V2, the exhaust damper 27, the flow rate adjusting unit 62 and the like of the coating unit are applied and developed as described later. It is controlled by a control unit 8 that controls the operation of the entire apparatus. The control unit 8 includes a computer having a program storage unit (not shown), for example. The program storage unit transfers the wafer W received from an external transfer means to the spin chuck 2 and moves the cover member 4 up and down. A computer program having a group of steps (commands) for the operation of applying a resist solution to the storage is stored. And when the said computer program is read by the control part 8, the control part 8 controls operation | movement of an application | coating unit. The computer program is stored in the program storage unit while being stored in a storage unit such as a hard disk, a compact disk, a magnetic optical disk, or a memory card.

  Based on the configuration described above, an operation of applying a resist solution to the wafer W performed in the coating unit will be described with reference to FIGS. First, as shown in FIG. 2A, the cover member 4 is raised to the delivery position, the spin chuck 2 is raised to the delivery position, and the wafer W is delivered to the spin chuck 2 from an external transfer means (not shown). (Step S1).

  Next, as shown in FIG. 2B, the spin chuck 2 is lowered to the processing position, and the cover member 4 is lowered to the coating position, thereby forming a space S1 surrounded by the periphery of the wafer W (step S2). . Then, while rotating the spin chuck 2 at a high speed at a first rotation speed, for example, about 4000 rpm, the resist liquid as the coating liquid is discharged from the coating liquid nozzle 6 toward the center of the wafer W (step S3). The first rotation speed is a rotation speed when adjusting the film thickness, and is a numerical value determined according to the film thickness of the resist film, and is set to, for example, 1000 rpm to 4500 rpm.

  Here, when rotating the spin chuck 2, the cover member 4 is also rotated at a high speed in the same rotational direction as the rotation of the spin chuck 2. At this time, the cover member 4 and the spin chuck 2 are preferably rotated at the same rotational speed, but the rotational speed of the cover member 4 may be a rotational speed within a range of the first rotational speed ± 500 rpm. The cover member 4 and the spin chuck 2 are preferably rotated while being synchronized with each other, but may be slightly shifted.

  At this time, the valve V1 is opened in the exhaust passage 26, the opening degree of the exhaust damper 27 is adjusted, and the inside of the cup 23 is lowered to a predetermined pressure, for example, about 5 to 20 Pa lower than the atmospheric pressure by the exhaust means 28. Exhaust. The reason why the inside of the cup 23 is slightly negative is to exhaust the mist in the cup 23 while preventing the inflow of air from the outside of the cup 23.

  In this way, in the enclosed space S1, the resist solution on the surface of the wafer W flows toward the outer edge side by the action of centrifugal force, and the excess resist solution on the wafer W is shaken off, and the cover member 4 and the lower plate 31 scatter outward. In this way, the wafer W is rotated at a high speed at the first rotation speed for about 10 to 20 seconds while the resist solution is being discharged to adjust the film thickness (step S4). The reason why the wafer W is rotated at a high speed while surrounding the periphery of the wafer W is to adjust the film thickness to a predetermined thickness while suppressing the formation of the wind mark, and the resist solution is supplied. The wafer W only needs to be rotated at a high speed at the first rotation speed, and the start timing of this high-speed rotation may be rotated after discharging the resist solution, or may be rotated while discharging the resist solution. Alternatively, the resist solution may be rotated before being discharged.

  After adjusting the resist film thickness, the rotational speed of the spin chuck 2 and the cover member 4 is gradually reduced. For example, as shown in FIG. 5, the second rotational speed lower than the first rotational speed in about 15 seconds. For example, the rotational speed is reduced to about 1800 rpm or less (step S5). At this time, the rotational speed of the cover member 4 is also gradually lowered together with the spin chuck 2. Here, the second number of rotations is the number of rotations required for removing the solvent in the resist solution while suppressing the occurrence of wind-off marks in the resist film on the wafer surface. For example, the number of ray nozzles (Re number) is It is a numerical value derived with consideration.

The Re number is expressed as follows: the distance from the center of the wafer W is r (mm), the angular velocity of the wafer W is ω (rad / s), and the gas dynamic viscosity coefficient around the wafer W is ν (mm ² / s). It is calculated by the following equation (1).

Re number = rω ² / ν (1)
If this Re number exceeds a certain value, non-uniform velocity of airflow occurs on the surface of the wafer W, and wind cut marks are easily formed. Therefore, in order to widen the region where the film thickness of the resist film is uniform, the Re number Must be reduced. When the wafer W is rotated, a laminar flow is formed at a location where the Re number <8 × 10 ⁴ on the wafer surface, and a transition flow is generated at a location where the 8 × 10 ⁴ <Re number <3 × 10 ^5. A turbulent flow is generated at a place where the number of Re is> 3 × 10 ⁵ . Since the non-uniform velocity is formed by the transition flow, in order to suppress the formation of the wind mark, it is required to suppress the generation of the transition flow, and based on this, the second rotational speed is determined as the transition flow. It is set to a slow speed that does not cause Thus, the second rotational speed is set to, for example, 500 rpm to 2000 rpm.

  Even in this case, the cover member 4 and the spin chuck 2 are preferably rotated at the same rotational speed, but the rotational speed of the cover member 4 may be any rotational speed within the range of the second rotational speed ± 500 rpm. The cover member 4 and the spin chuck 2 are preferably rotated while being synchronized with each other, but may be slightly shifted.

  Thereafter, in a state in which the rotation number of the spin chuck 2 and the rotation number of the cover member 4 are set to the rotation number equal to or less than the second rotation number, the cover member 4 is gradually opened while rotating, and the cover member 4 is opened. The position is raised to the drying position in about 5 seconds, for example (FIG. 3A, step S6). In this way, the periphery of the wafer W is in an open state, so that the solvent contained in the resist solution is likely to volatilize and the volatilization is promoted (step S7). Note that the cover member 4 is rotated with the rotation of the spin chuck 2 even in the dry position, and the exhaust of the cup 23 is continued.

  Thus, by rotating both the spin chuck 2 and the cover member 4 in the same direction for a predetermined time, for example, about 20 seconds, the solvent in the resist film is sufficiently volatilized, and the remaining resist component has a thickness of, for example, 0. A 6 μm resist film is formed. After the resist film is formed in this way, the rotation of the cover body 4 and the spin chuck 2 is stopped, and the cover body 4 and the spin chuck 2 are raised to their delivery positions, and the wafer W is delivered to an external transfer means (not shown) (FIG. 3 ( b)).

  As described above, in the present invention, at the stage of adjusting the film thickness of the resist film, the upper plate 41 of the cover member 4 is brought close to the surface of the wafer W to surround the wafer W together with the fixing member, and the space surrounded by the periphery of the wafer W. Since both the spin chuck 2 and the cover member 4 are rotated at a high speed by the first rotation speed in a state where S1 is formed, one type of coating liquid is used in the conventional spin coating method while suppressing the formation of wind-off marks. A thin resist film that has been difficult to adjust can be formed in a wide region.

  In other words, in the configuration of the present invention, since the wafer W supplied with the resist solution is rotated at a high speed while being placed in the enclosed space S1, the inflow of air from the outside to the periphery of the wafer during this rotation is suppressed. It is done. For this reason, since a turbulent airflow is not easily formed on the wafer surface, the formation of wind-cut marks is suppressed even when the wafer is rotated at a high speed, and the film thickness can be reduced as compared with the case where the cover member 4 is not used. Here, since the film thickness of the resist film is adjusted by the number of rotations of the wafer W, the film thickness can be reduced as compared with the conventional film. growing.

  At this time, since the spin chuck 2 and the cover member 4 are rotated in the same rotational direction, the air on the wafer surface also rotates as the spin chuck 2 and the cover member 4 rotate. Therefore, the airflow is less likely to be disturbed on the wafer surface, and the formation of wind-cut marks is suppressed, and the in-plane uniformity of the resist film thickness is improved. On the other hand, if the rotation speed of the cover member 4 is greatly deviated from the first rotation speed range or the rotation direction is different, the airflow between the airflow rotating with the wafer W and the airflow rotating with the cover member 4 is reduced. Disturbances occur, and the surface of the wafer W is affected by gas friction, so that a wind cut mark is easily formed.

  Further, on the side of the wafer W held by the spin chuck 2, the wall member 32 and the side wall portion 42 are in a state of overlapping each other in the vertical direction, and it is assumed that there is a gap between the wall member 32 and the lower plate 31. Even if air is about to flow in, it collides with the wall member 32, flows along the wall member 32, and flows through the gap between the wall member 32 and the upper plate 41. Therefore, the side of the wafer W has a structure in which air hardly enters the inside, and this structure also suppresses the turbulence of the air current near the surface of the wafer due to the inflow of air from the outside of the cover member 4.

In addition, after adjusting the film thickness of the resist film, the rotational speed is reduced to a second rotational speed or less determined based on the Re number, and then the drying position is rotated while the cover member 4 is rotated in the same rotational direction as the spin chuck 2. Has moved up. Thus, when the cover member 4 is opened, the cover member 4 is rotated together with the spin chuck 2, so that the cover member 4 can be opened in a state where turbulence of the air current on the wafer surface is suppressed. On the other hand, when the rotation of the cover member 4 is stopped, the airflow in the vicinity of the cover member 4 and the airflow rotating together with the wafer W are different in the formation state of the airflow. It becomes easy to do. Further, as described above, since the second rotational speed is a numerical value obtained to suppress the formation of the wind-off mark, even if an open space is formed around the wafer W in this step. Wind cut marks are difficult to form.

  And by opening the cover member 4 in this way, the volatilization of the solvent in the resist solution is promoted, and the volatilization of the solvent is performed quickly. For this reason, even when the drying time is about the same as the conventional one, the occurrence of film unevenness due to natural drying is suppressed, and a resist film with good in-plane uniformity can be formed. Further, since the cover member 4 is rotated together with the spin chuck 2 during the drying, the turbulence of the air current on the surface of the wafer W can be suppressed.

  Furthermore, the rotation of the cover member 4 and the spin chuck 2 is not stopped from the stage of adjusting the film thickness of the coating film to the stage of volatilizing the solvent in the coating film, and the cover member 4 and the spin chuck 2 are rotated in the same rotational direction. Therefore, even if the rotational speed is lowered in the middle, the airflow on the wafer W flows in a stable state. For this reason, the turbulence of the airflow on the wafer W can be suppressed as compared with the case where the rotation of both the cover member 4 and the spin chuck 2 is stopped halfway or the rotation of either one is stopped.

  Next, a second embodiment of the present invention will be described. The coating unit of this example is configured so that gas can be supplied between the cover member 4 and the wafer W on the spin chuck 2 via the cover member 4. Hereinafter, differences from the above-described first embodiment will be described. In this example, a ventilation portion 71 is provided in the cover member 4 as shown in FIG. The ventilation portion 71 is made of, for example, a porous body made of PTFE (polytetrafluoroethylene). For example, the central portion of the upper plate 41 of the cover member 4, that is, an opening for supplying a resist solution from the coating solution nozzle 6. For example, along the circumferential direction, a region around 41a and a region facing the peripheral side of the wafer W placed on the spin chuck 2 are provided. The thickness of the ventilation portion 71 is set to about 3 to 5 mm, and may be disposed on the upper plate 41 at intervals along the circumferential direction, or may be disposed in a ring shape. Further, instead of providing a porous body, a large number of air holes may be formed in the upper plate 41.

A flat vent chamber 72 is formed on the upper side of the cover member 4 so as to cover the vent portion 71, and this vent chamber 72 is connected to the vicinity of the bottom of the rotation holding portion 51 formed in a cylindrical shape. The ventilation space S <b> 2 is formed above the upper plate 41 together with the space formed inside the rotation holding part 51. On the other hand, a gas supply path 73 is connected to the cylindrical support section 52 at the upper part of the rotation holding section 51, and the other end side of the gas supply path 73 is made from air via a valve V3 and a flow rate adjustment section 74a. Is connected to a supply source 74 of a low-viscosity first gas such as He gas, and to a second gas such as an air supply source 75 via the valve V4 and the flow rate adjusting unit 75a. It is connected.
Here, the ventilation space S2, the gas supply path 73, the valve V3 and the flow rate adjusting unit 74a, and the He gas supply source 74 constitute a first gas supply means, and the ventilation space S2, the gas supply path 73, the valve V4, The flow rate adjusting unit 75a and the air supply source 75 constitute a second gas supply unit. As the first gas, neon (Ne) gas, nitrogen (N ₂ ) gas, or the like can be used in addition to He gas, and as the second gas, oxygen (O ₂ ) gas in addition to air. Alternatively, argon (Ar) gas or the like can be used. In this way, gas is supplied from the gas supply path 73 to the ventilation chamber 72 through the internal space of the support portion 52 and the internal space of the rotation holding portion 51, and the gas supplied into the ventilation chamber 72 passes through the ventilation portion 71. The air is vented to the lower side of the cover member 4. Other configurations are the same as those in the first embodiment.

Based on the configuration described above, the operation of applying the resist solution to the wafer W performed by the coating unit will be described with reference to FIGS. First, the cover member 4 is raised to the delivery position, the spin chuck 2 is raised to the delivery position, and the wafer W is delivered to the spin chuck 2 from an external transfer means (not shown) (step S11). Next, the spin chuck 2 is lowered to the processing position, and the cover member 4 is lowered to the coating position, thereby forming a space S1 surrounded by the wafer W (step S12).
Then, the valve V3 is opened, He gas is introduced into the support portion 52 from the gas supply path 73 at a flow rate of, for example, about 20 sccm, and the opening degree of the exhaust damper 27 in the exhaust path 26 is increased to increase the pressure in the cup 23. Is adjusted so that the pressure becomes slightly negative pressure, for example, about 5 to 20 Pa lower than atmospheric pressure. In this state, the resist solution is discharged from the coating solution nozzle 6 toward the center of the wafer W while rotating both the spin chuck 2 and the cover member 4 in the same direction at a first rotation number, for example, about 4000 rpm. (FIG. 7A, step S13).
In this way, in the enclosed space S1 formed by the cover member 4 and the lower plate 31, the inside of the cup 23 is evacuated to a slight negative pressure, while the ventilation portion of the cover member 4 is exhausted. Since He gas is supplied into the space S1 via 71, the air in the space S1 is gradually replaced with He gas. On the other hand, the resist solution on the surface of the wafer W flows toward the outer edge side by the action of centrifugal force, and surplus resist solution on the wafer W is further shaken off. The resist solution thus shaken off is formed between the cover member 4 and the lower plate 31. Spattering from outside to outside. Thus, the film thickness is adjusted by rotating the wafer W at a high speed for about 15 seconds while discharging the resist solution (step S14).

  In the enclosed space S1, air is replaced with He gas having a lower viscosity than the air, and in such an atmosphere having a low viscosity, the Re number is small and it is difficult to form a wind cut mark. Mark formation is suppressed. That is, as described above, when the Re number exceeds a certain value, wind-cut marks are easily formed. Therefore, in order to widen the region where the film thickness of the resist film is uniform, it is necessary to reduce the Re number. Become.

Here, the value of the gas dynamic viscosity coefficient ν (mm ² / s) is calculated by the following equation (2). In the equation (2), μ is the viscosity coefficient (Pas · s) of the gas around the wafer, and ρ is the density (kg / m ³ ) of the gas.

ν = μ / ρ (2)
Therefore, in order to reduce the Re number, the gas kinematic viscosity coefficient ν may be increased. For this purpose, a gas having a low density ρ, that is, a gas having a low viscosity may be used. After adjusting the resist film thickness while suppressing the formation of wind-off marks in this way, the rotational speeds of the spin chuck 2 and the cover member 4 are gradually decreased, and as described above, the second rotational speed, for example, about 1800 rpm or less. (Step S15). At this time, the cover member 4 is rotated together with the spin chuck 2 in the same direction, and the rotational speed thereof is gradually decreased together with the spin chuck 2. Also at this stage, the supply and exhaust of He gas are continued.

  Here, the space S1 may be replaced with the He gas until the solvent is volatilized after the wind-cut mark is formed, that is, after the film thickness of the resist film is adjusted. Either before or after the resist solution is discharged. Further, after the replacement with He gas, the supply of He gas may be stopped, and the opening amount of the exhaust damper 27 may be reduced to make the exhaust amount smaller than when He gas is supplied. At this time, if exhaust is completely stopped, the mist generated in the space S1 cannot be removed. Therefore, it is desirable to reduce the exhaust amount to such an extent that the cup 23 has a slight negative pressure.

  Thereafter, the valve V3 is closed, the valve V4 is opened, the gas supplied through the cover member 4 is switched from He gas to air, the air is supplied at a flow rate of about 20 sccm, and the exhaust damper 27 is opened. The inside of the cup 23 is exhausted so that the pressure in the cup 23 is slightly negative pressure, for example, about 5 to 20 Pa lower than the atmospheric pressure. In this state, the cover member 4 is gradually raised while the spin chuck 2 and the cover member 4 are rotated in the same direction at a rotation speed equal to or less than the second rotation speed, and the cover member 4 is raised to the drying position. (FIG. 7B, step S16).

  By doing so, the cover member 4 is raised while supplying air to the center side and the peripheral side of the wafer surface via the cover member 4. Therefore, when the cover member 4 is opened, the cover member Even if air is about to flow in from the outside, the air supplied from the inside of the cover member 4 is suppressed from flowing in, and as a result, the turbulence of the air current on the surface of the wafer W is suppressed. Further, by supplying air to the surface of the wafer W, volatilization of the solvent in the resist solution is promoted. Here, air is supplied instead of He gas in order to reduce the operating cost, but He gas may be supplied also in this step.

  Thus, the cover member 4 is positioned at the drying position, and the solvent is volatilized while rotating both the cover member 4 and the spin chuck 2 in the same direction at a rotation speed equal to or lower than the second rotation speed (step S7). . At this time, depending on the type and film thickness of the resist solution, the solvent contained in the resist solution may be volatilized while supplying air, or the supply of air is stopped and the solvent contained in the resist solution is stopped. May be volatilized, but the opening degree of the exhaust damper 27 is adjusted according to the amount of air supplied to prevent the occurrence of wind-off marks. That is, if the negative pressure in the cup 23 is increased, air enters from the outside of the cup 23, the airflow on the surface of the wafer W is disturbed, and a wind-off mark is generated, so that the mist is removed from the inside of the cup 23. When the air is supplied, the opening of the exhaust damper 27 is increased so that the negative pressure is such that the air does not enter through, for example, a pressure lower than the atmospheric pressure by about 5 to 20 Pa. When the air is not supplied, the air is supplied. The exhaust control in the cup 23 is performed so that the opening degree of the exhaust damper is made smaller.

  Thus, by rotating both the spin chuck 2 and the cover member 4 in the same direction for a predetermined time, for example, about 15 seconds, the solvent in the resist solution is sufficiently volatilized, and a resist film is formed on the surface of the wafer W by the remaining resist component. . After the resist film is formed in this way, the supply of air is stopped, the inside of the cup 23 is kept at a pressure lower by about 5 Pa than the atmospheric pressure, the rotation of the cover body 4 and the spin chuck 2 is stopped, and these are transferred to each other. The wafer W is raised to a position, and the wafer W is delivered to an external transfer means (not shown) (step S8).

  Even in such a configuration, in the stage of adjusting the film thickness of the resist film, the atmosphere in the space S1 is replaced with a gas having a viscosity lower than that of air in a state where the space S1 surrounded by the periphery of the wafer W is formed. Therefore, as described above, the formation of wind-cut marks is suppressed, and the adjustment range of the film thickness of the resist film is increased even when one type of coating liquid is used.

  In the step of volatilizing the solvent in the resist solution, air is supplied between the cover member 4 and the wafer W via the cover member 4, and as described above, the air flow near the surface of the wafer W is reduced. While suppressing disturbance, volatilization of the solvent can be promoted, and the time required for volatilization of the solvent can be shortened. For this reason, even when the drying time is about the same as the conventional one, the occurrence of uneven coating due to natural drying can be suppressed, and a resist film with good in-plane uniformity can be formed.

  Next, an example of a resist pattern forming system in which an exposure unit (exposure apparatus) is connected to a coating / developing apparatus incorporating the coating apparatus will be briefly described. 9 is a plan view of the system, FIG. 10 is a perspective view of the system, and FIG. 11 is a sectional view of the system. In this apparatus, a carrier block S1 is provided. In this block S1, the transfer arm C takes out the wafer W from the hermetically sealed carrier 100 mounted on the mounting table 101 and is adjacent to the block S1. In addition, the transfer arm C is configured to receive the processed wafer W processed in the process block S2 and return it to the carrier 100.

  In the processing block S2, in this example, a first block (DEV layer) B1 for performing development processing, and a second block (for forming an antireflection film formed on the lower layer side of the resist film) ( BCT layer) B2, a third block (COT layer) B3 for applying a resist solution, and a fourth block (TCT layer) for forming an antireflection film formed on the upper layer side of the resist film ) B4 is laminated in order from the bottom.

  The second block (BCT layer) B2 and the fourth block (TCT layer) B4 are performed by a coating unit that applies a coating solution for forming an antireflection film by spin coating, and this coating unit. Heating / cooling processing unit groups for performing pre-processing and post-processing, and transfer arms A2 and A4 that are provided between the coating unit and the processing unit group, and transfer wafers W between them. It is comprised by. The third block (COT layer) B3 has the same configuration except that the coating solution is a resist solution.

  On the other hand, for the first processing block (DEV layer) B1, as shown in FIGS. 10 and 11, the developing units 102 are stacked in two stages in one DEV layer B1. In the DEV layer B1, a transfer arm A1 for transferring the wafer W to the two-stage development unit is provided. That is, the transport arm A1 is shared by the two-stage developing unit 102.

  Further, as shown in FIG. 9 and FIG. 11, the processing block S2 is provided with a shelf unit U5, and between the parts of the shelf unit U5, a first freely movable up and down provided in the vicinity of the shelf unit U5. The transfer arm D1 carries the wafer W.

  The wafers W from the carrier block S1 are sequentially transferred by the transfer arm C to one transfer unit of the shelf unit U5, for example, the transfer unit CPL2 corresponding to the second block (BCT layer) B2. The transfer arm A2 in the second block (BCT layer) B2 receives the wafer W from the transfer unit CPL2 and transfers it to each unit (antireflection film unit and heating / cooling processing unit group). Thus, an antireflection film is formed on the wafer W.

  Thereafter, the wafer W is transferred into the third block (COT layer) B3 via the transfer unit BF2, the transfer arm D1, the transfer unit CPL3 of the shelf unit U5, and the transfer arm A3, thereby forming a resist film. . Further, the wafer W is transferred to the transfer unit BF3 in the shelf unit U5 through the transfer arm A3, the transfer unit BF3 of the shelf unit U5, and the transfer arm D1. The wafer W on which the resist film is formed may further have an antireflection film formed in the fourth block (TCT layer) B4. In this case, the wafer W is transferred to the transfer arm A4 via the transfer unit CPL4, and after the antireflection film is formed, the wafer W is transferred to the transfer unit TRS4 by the transfer arm A4.

  On the other hand, on the upper part in the DEV layer B1, a shuttle arm E, which is a dedicated transfer means for directly transferring the wafer W from the transfer unit CPL11 provided in the shelf unit U5 to the transfer unit CPL12 provided in the shelf unit U6. Is provided. The wafer W on which the resist film and further the antireflection film are formed is transferred to the transfer unit CPL11 by the transfer arm D1 via the transfer units BF3 and TRS4, and from here to the transfer unit CPL12 of the shelf unit U6 directly by the shuttle arm E. It is conveyed and taken into the interface block S3. In FIG. 11, the delivery unit attached with CPL also serves as a cooling unit for temperature control, and the delivery unit attached with BF also serves as a buffer unit on which a plurality of wafers W can be placed. Yes.

  Next, the wafer W is transferred by the interface arm B to the exposure apparatus S4, where a predetermined exposure process is performed, and then placed on the transfer unit TRS6 of the shelf unit U6 and returned to the processing block S2. The returned wafer W is developed in the first block (DEV layer) B1, and is transferred by the transfer arm A1 to the transfer table in the access range of the transfer arm C in the shelf unit U5. And returned to the carrier 100. In FIG. 9, U <b> 1 to U <b> 4 are thermal system unit groups in which a heating unit and a cooling unit are stacked.

  Using the experimental apparatus shown in FIG. 12, the number of rotations of the spin chuck and the resist film when the resist film is formed with the wafer W surrounded by the cover member and the spin chuck and when the cover member is not used. The relationship with the film thickness was measured and compared.

  First, the experimental apparatus will be briefly described. In FIG. 12, reference numeral 91 denotes a spin chuck. A side wall 92 is provided around the periphery of the spin chuck 91, and a cover is provided at the upper end of the side wall 92. The member 93 is configured to be attached by screwing. Here, the distance between the upper surface of the spin chuck 91 and the lower surface of the cover member 93 was set to 5 mm, and the distance between the surface of the wafer W and the lower surface of the cover member 93 was set to 4 mm.

  Then, the wafer W is held on the spin chuck 91, and a resist solution is supplied to the center of the wafer. Then, the cover member 93 is attached to the spin chuck 91, and the spin chuck S is placed in the space surrounded by the wafer W. The film thickness was measured at a rotation speed of 1800 rpm, 3000 rpm, and 4200 rpm, and in each case, the film thickness was measured after a predetermined time. Similarly, the same experiment was performed with the front side of the wafer opened without providing a cover member. These results are shown in FIG. In the figure, “Close” refers to the case where the cover member 93 is provided, and “Open” refers to the case where the cover member is not provided. The resist solution used at this time is a krF resist having a concentration of 3 cp.

  From this result, it was confirmed that when the wafer is surrounded by the cover member 93 and the spin chuck 91, the film thickness range in the thin film direction of the resist film can be expanded as compared with the case where the cover member 93 is not used. When the cover member 93 is not used, the change in the film thickness is small even when the rotation time is extended. However, when the cover member 93 is used, the change in the film thickness is large even after the rotation time exceeds 20 seconds. It is recognized that the film thickness can be controlled by adjusting the rotation time even if the rotation speed is the same.

  However, when the cover member 93 is provided in the above-described embodiment, the cover member is opened after the rotation time of 5 seconds elapses to stop the rotation of the spin chuck 91, and the state of the resist film is visually observed after about 60 seconds elapses. When confirmed, generation | occurrence | production of the film | membrane nonuniformity was recognized. Therefore, in the state where the wafer W is surrounded by the cover member 93, the solvent is not sufficiently volatilized, and the solvent remains in the film. It is presumed that this has been caused.

  Based on this, after the rotation time of 10 to 60 seconds passed, the cover member 93 was opened, and then the spin chuck 91 was rotated at the same rotation speed for about 10 seconds, and then the state of the resist film was visually confirmed. However, film unevenness was not confirmed. From this, it is recognized that when the cover member 93 is opened and the spin chuck 91 is rotated, the evaporation of the solvent is promoted, and the solvent in the film is sufficiently evaporated in about 10 seconds after the cover member 93 is opened. It was. At this time, when the rotational speed is 3000 rpm or 4200 rpm, the occurrence of a wind-off mark is recognized, but when the rotational speed is 1800 rpm, the wind-off mark is not confirmed. Therefore, the lower the rotational speed, the more the wind-off mark is formed. Is understood to suppress.

  In the above, in the present invention, it is preferable that the cover member 4 and the spin chuck 2 are rotated in synchronization with each other, but the rotation speed of the cover member 4 is within a range set in advance from the rotation speed of the spin chuck 2. If it is a number, the effect of the present invention can be obtained, and the timing of the start and stop of rotation may be shifted.

  The shape of the cover member 4 is not limited to the above example, and when the upper plate 41 approaches the wafer placed on the spin chuck 2, the cover member 4 is placed on the spin chuck 2 together with the fixing member or alone with the cover member 4. Any shape may be used as long as it covers the surface and the side of the wafer. That is, if the shape covers the surface and the side of the wafer placed on the spin chuck 2, the flow of airflow from the outside can be suppressed to some extent without forming the space S1 surrounded by the wafer. This is because the occurrence of air current turbulence on the wafer surface can be sufficiently suppressed.

  The cover member 4 may be moved up and down relatively with respect to the spin chuck 2. For example, the cover member 4 may be moved closer to the wafer W by moving up and down the spin chuck 2 side. At this time, the cup 23 is also configured to be movable up and down. When the wafer W is transferred between the spin chuck 2 and the external transfer means, the cup 23 is lowered, and when the coating process is performed on the wafer W, the cup 23 is moved. It may be raised.

  Furthermore, the cover member 4 of the present invention may be rotated by a rotation mechanism common to the spin chuck 2. Furthermore, the present invention can be applied to a coating treatment of an antireflection film, an insulating material, etc. in addition to the coating treatment of the resist solution. In addition to the semiconductor wafer W, the present invention can also be applied to processing of an LCD substrate, a mask substrate, and the like.

It is sectional drawing which shows the coating device which concerns on this invention. It is sectional drawing for demonstrating the coating method performed with the said coating device. It is sectional drawing for demonstrating the coating method performed with the said coating device. It is process drawing for demonstrating the said coating method. It is a characteristic view which shows the relationship between the rotation speed and rotation time for demonstrating the said coating method. It is sectional drawing which shows the coating device which concerns on other embodiment of this invention. It is sectional drawing for demonstrating the coating method performed with the said coating device. It is process drawing for demonstrating the said coating method. It is a top view which shows the resist pattern formation apparatus incorporating the said coating device. It is a perspective view which shows the said resist pattern formation apparatus. It is sectional drawing which shows the said resist pattern formation apparatus. It is sectional drawing which shows the coating device for experiment. It is a characteristic view which shows the relationship between the film thickness of a resist liquid, and rotation speed.

Explanation of symbols

W Wafer M1, M2 Motor (Rotation mechanism)
2 Spin chucks 22 and 57 Elevating mechanism 23 Cup 31 Lower plate 32 Wall member 4 Cover member 41 Upper plate 42 Side wall portion 51 Rotation holding portion 6 Coating liquid nozzle 8 Control portion

Claims (12)

A substrate holding unit that holds the substrate substantially horizontally and rotates around a vertical axis;
A cover member that is provided on the upper side of the substrate held by the substrate holding part and that is provided with an upper plate that faces the substrate through a gap and is provided to be rotatable about a vertical axis,
An elevating mechanism for elevating the cover member relative to the substrate holder;
A coating liquid nozzle for supplying a coating liquid containing a coating film component and a solvent to the substrate surface held by the substrate holding unit;
A control unit that controls the operation of the substrate holding unit, the cover member, and the lifting mechanism,
The control unit moves the upper plate closer to the substrate surface and rotates the substrate holding unit and the cover member in the same direction, thereby centrifugally applying the coating liquid supplied to the center portion of the substrate surface. And adjusting the film thickness of the coating film by stretching by
Next, while rotating the substrate holding part and the cover member at a lower rotational speed than the step, raising the cover member relative to the substrate holding part to volatilize the solvent in the coating film; A coating apparatus configured to perform A fixing member including an annular member formed in an annular shape in the circumferential direction of the substrate through the gap on the back surface side of the substrate held by the substrate holding unit;
The coating apparatus according to claim 1, wherein the cover member is configured to surround the substrate together with the fixing member when approaching the substrate.   The coating apparatus according to claim 1, wherein the cover member is configured to be rotatable by a rotation mechanism different from the substrate holding unit.   The coating apparatus according to claim 1, wherein the coating liquid nozzle is provided on the cover member. A first gas supply means for supplying a first gas having a viscosity lower than that of air between the cover member and the substrate held by the substrate holding portion via the cover member;
The control unit outputs a control signal for supplying the first gas when the cover member is rotated at a rotation speed for adjusting the film thickness of the coating film. The coating apparatus as described in any one of thru | or 4. A second gas supply unit configured to supply a second gas different from the first gas between the cover member and the substrate held by the substrate holding unit via the cover member;
The control unit outputs a control signal for supplying a second gas instead of the first gas when the cover member is raised relative to the substrate holding unit. The coating apparatus according to claim 5. A cup covering the side and lower side of the substrate held by the substrate holding unit;
Exhaust means for exhausting the atmosphere in the cup;
An exhaust amount adjusting unit for adjusting the exhaust amount of the exhaust means in order to adjust the atmosphere in the cup to a predetermined pressure,
The control unit increases the exhaust amount when supplying gas through the cover member, and reduces the exhaust amount when supplying gas through the cover member rather than when supplying gas through the cover member. 7. The coating apparatus according to claim 5, wherein a control signal is output so as to be small. A step of holding the substrate substantially horizontally on the substrate holding portion;
Supplying a coating solution containing a component of the coating film and a solvent to the center of the substrate held by the substrate holding unit;
An upper plate facing the said substrate through a gap on the upper side of the substrate held by the substrate holding section, rotatably provided around a vertical axis, the larger the cover member than the substrate, wherein the upper plate Locating at a position approaching the substrate surface;
Next, by rotating the substrate holding portion and the cover member in the same direction, the coating liquid on the substrate surface is extended by centrifugal force to adjust the film thickness of the coating film;
Next, while rotating the rotation speed of the substrate holding part and the cover member at a lower rotation speed than that in the step, the cover member is raised relative to the substrate holding part to volatilize the solvent in the coating film. A coating method comprising the steps of:   When the cover member is rotated at a rotation speed for adjusting the film thickness of the coating film, a first gas having a lower viscosity than air is supplied between the cover member and the substrate. The coating method according to claim 8. When the cover member is raised relative to the substrate holding portion, a second different from the first gas is used instead of the first gas between the cover member and the substrate. A gas is supplied, The coating method of Claim 9 characterized by the above-mentioned. Comprising a cup for covering the lateral side and the lower side of the substrate held by the substrate holding unit, when supplying gas between the front Symbol cover member and the substrate are evacuated in greater displacement volume within the cup, the cover When the gas is not supplied between the member and the substrate, the pressure in the cup is adjusted by exhausting the inside of the cup with a smaller displacement than when supplying the gas between the cover member and the substrate. The coating method according to claim 9 or 10, wherein A memory storing a computer program used in a coating apparatus for supplying a coating liquid to a central portion of a substrate held substantially horizontally by a substrate holding section and rotating the substrate holding section to apply the coating liquid to the surface of the substrate. A medium,
12. A storage medium in which the program includes a set of steps so as to execute the coating method according to claim 8.

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