JP2015211170A - Coating device, coating method, and memory medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a coating film with excellent uniformity of film thickness within a plane of a substrate.SOLUTION: A coating film is formed from a resist solution by discharging the resist solution diluted with a solvent onto a surface of a wafer W rotating around a vertical axis while evacuating a process atmosphere where the wafer W is placed. Then evacuation of the process atmosphere is stopped; and while a solvent atmosphere generating from the resist liquid thrown off from an outer edge of the wafer W is formed in an outer periphery of the wafer W, the wafer W is rotated around the vertical axis, and the resist solution on the surface of the wafer W is dried.

Description

  The present invention relates to a coating apparatus, a coating method, and a storage medium in which the coating method is recorded, which forms a coating film on an object to be processed.

  In a series of processes for manufacturing semiconductor devices, a resist film, polyimide film, adhesive film (film made of an adhesive), etc., for a semiconductor wafer (hereinafter referred to as “wafer”) which is a substrate (object to be processed) There is a step of forming a coating film. Such a coating film is used as a coating solution obtained by diluting an organic material constituting the coating film with a solvent such as thinner. And after discharging this coating liquid to the center part of a wafer, a wafer is rotated to the surroundings of a vertical axis, a liquid film is spread toward the peripheral edge of the said wafer, and this liquid film is then dried (solvent) The coating film is formed.

  Here, in order to meet the recent demand for miniaturization of semiconductor devices, a vertically stacked structure (stacked structure) of so-called “3D NAND” has been studied. In such a structure, since the etching process is continuously performed on the laminated body in which the organic film containing carbon and the silicon-based inorganic film are alternately laminated, the resist film disposed on the upper layer side of the laminated body Is formed so as to be a thick film of several μm, for example.

By the way, the method of spreading the resist solution on the wafer by centrifugal force tends to increase the film thickness at the peripheral portion rather than at the central portion of the wafer. That is, when the wafer is rotated around the vertical axis and the coating liquid is shaken off from the periphery of the wafer, the outer peripheral edge of the wafer is more easily exposed to the outside air than the center side. Therefore, when the coating liquid flows from the center side of the wafer toward the outer peripheral side by centrifugal force, the solvent quickly evaporates on the outer peripheral side and the coating liquid does not flow easily. In addition to the fact that the viscosity is higher than that of the resist solution for the thin film, the liquid is accumulated on the outer periphery of the wafer. In other words, even if an excess coating solution is removed from the outer peripheral portion of the wafer by centrifugal force, the extra coating solution remains on the outer peripheral portion. Therefore, the in-plane uniformity of the coating film is further deteriorated.
Patent Document 1 describes a coating processing apparatus provided with a slat that can be opened and closed so as to face the outer peripheral portion of a wafer. However, a technique that can further improve the uniformity of a coating film is required.

JP2003-179041

  The present invention has been made under such circumstances, and an object of the present invention is to provide a technique capable of forming a coating film having excellent film thickness uniformity in the plane of the substrate.

The coating apparatus of the present invention is
In an apparatus for forming a coating film by applying a coating liquid containing a solvent to a substrate, which is disposed in an atmosphere in which a downflow of clean gas is formed,
A substrate holding unit that holds the substrate horizontally and is rotatable about a vertical axis;
A coating liquid nozzle that discharges the coating liquid onto the surface of the substrate held by the substrate holding unit;
A cup body provided so as to surround the substrate held by the substrate holding portion;
An exhaust path for exhausting the internal atmosphere of the cup body;
When the coating liquid is applied by the rotation of the substrate, the exhaust path exhausts, and when the substrate rotates to dry the coating liquid on the substrate, the exhaust amount by the exhaust path is set to zero. And a control unit that outputs a control signal.
The exhaust amount zero includes the case where the flow rate Va is substantially zero, and includes the case where the exhaust flow rate is less than 1.3 m ³ / min (the exhaust pressure at the exhaust port is less than 25 Pa), for example.

The coating method of the present invention comprises:
In a method of forming a coating film by applying a coating liquid containing a solvent to a substrate in an atmosphere in which a clean downward airflow is formed,
Holding the substrate horizontally on the substrate holder;
A cup body is provided so as to surround the substrate while supplying the coating solution to the central portion of the substrate and rotating the substrate holding portion around the vertical axis to spread the coating solution on the substrate and apply the coating solution. Exhausting the internal atmosphere through the exhaust path;
And a step of rotating the substrate holding part to dry the coating liquid on the substrate in a state where the exhaust amount by the exhaust path is zero.
The storage medium of the present invention is
A storage medium storing a computer program that runs on a computer,
The computer program is characterized in that steps are set so as to implement the above-described coating method.

  In the present invention, when the coating liquid is applied to the substrate to form the coating film, the coating liquid is discharged from the coating liquid nozzle to apply the coating liquid, while exhausting the atmosphere in which the substrate is placed. When the film is dried, the amount of exhaust is reduced compared to when the coating liquid is discharged. Therefore, when the coating solution is dried, an atmosphere of a solvent contained in the coating solution can be formed on the peripheral portion of the substrate. Accordingly, since the solvent is less likely to evaporate from the coating solution at the peripheral edge of the substrate, the coating liquid that flows from the central portion of the substrate toward the peripheral portion can be quickly discharged from the peripheral edge by centrifugal force. A coating film having excellent properties can be formed.

It is a perspective view which shows the resist coating device of this invention. It is a longitudinal cross-sectional view which shows the said coating device. It is a top view which shows the said coating device. It is the schematic which shows the effect | action of the said coating device. It is the schematic which shows an example of the control part provided in the said coating device. It is a conceptual diagram which shows the time chart of each process in the said coating device. It is a longitudinal cross-sectional view which shows the effect | action of the said coating device. It is a longitudinal cross-sectional view which shows the effect | action of the said coating device. It is a longitudinal cross-sectional view which shows the effect | action of the said coating device. It is a longitudinal cross-sectional view which shows the effect | action of the said coating device. It is a longitudinal cross-sectional view which shows the other example of the said coating device. It is a longitudinal cross-sectional view which expands and shows a part of coating device in the said other example. It is a longitudinal cross-section which shows another example of the said coating device. It is a characteristic view which shows the result obtained in the Example of this invention. It is a characteristic view which shows the result obtained in the Example of this invention.

  An example of a coating apparatus (resist coating apparatus) according to an embodiment of the present invention will be described with reference to FIGS. In this resist coating apparatus, as shown in FIG. 1, a processing unit that applies a resist liquid (processing liquid) to a wafer W, which is a substrate (object to be processed), and forms a resist film (coating film). 11 is provided side by side and in two places in this example. Each processing unit 11 is provided with an exhaust path 31 for exhausting the processing atmosphere in which the wafer W is placed, and these exhaust paths 31 are provided in the exhaust path 31 as will be described in detail later. A damper 48, which is an opening / closing part for opening / closing the flow path and adjusting the pressure (flow velocity), is interposed. In the present invention, by adjusting the opening degree of the damper 48, the film thickness dimension of the resist film applied to the surface of the wafer W is made uniform over the entire surface. Next, details of the resist coating apparatus and a resist solution coating method will be described below. In FIG. 1, reference numeral 10 denotes a base on which the processing units 11 are placed. Further, reference numeral 49 in FIG. 1 is an exhaust duct provided in common throughout the factory, and is therefore shared by the respective processing units 11. In FIG. 1, each processing unit 11 is schematically simplified and drawn.

  On the base 10, rails 22 formed along the arrangement of the processing units 11 are provided. On the rails 22, the collective nozzles 1 supported by the arms 21 pass through the arms 21 in the horizontal direction. It is arranged to move freely. On the lower surface side of the collective nozzle 1, a nozzle 24 is provided as a discharge unit that discharges a plurality of types of solvents such as resist solutions and thinners. On the upstream side of the nozzle 24 that discharges the resist solution, a storage portion 21a in which the resist solution is stored is provided, and this resist solution is diluted with a solvent such as thinner. The viscosity of the diluted resist solution in the storage unit 21a is, for example, 1 cP to 300 cP at 25 ° C. In FIG. 1, reference numeral 21b denotes a solvent reservoir. In FIG. 1, the resist solution storage portion 21 a is drawn by representing only one of the plurality of storage portions 21 a.

  Further, as shown in FIG. 1, a rail 18 is formed on the base 10 at a position facing each processing unit 11, and an arm 17 having an auxiliary nozzle 15 attached to the upper end of the rail 18 is formed. It is arranged to be movable in the horizontal direction. The auxiliary nozzle 15 is for discharging a solvent (thinner) in order to remove the resist film from the peripheral edge of the wafer W on which the resist film is formed. In FIG. 1, 16 a is a nozzle bath for retracting the auxiliary nozzle 15, and 16 b is a nozzle bath for retracting the collective nozzle 1. The liquid feeding pump, each valve, or the flow rate adjusting unit combined with the nozzles 15 and 24 and the storage unit 21a constitute a chemical solution supply device 110 described later. In FIG. 1, reference numeral 72 denotes lifting pins for lifting the wafer W. In FIG. 2, the collective nozzle 1 and the auxiliary nozzle 15 are illustrated in a simplified manner, and the lifting pins 72 are not shown.

  Next, the processing unit 11 will be described. As shown in FIG. 2, the processing unit 11 is provided with a spin chuck 14 for sucking and holding the wafer W horizontally from the back side as a substrate holding unit. The spin chuck 14 is a spin chuck motor or the like. The rotary mechanism 14a is configured to be rotatable around the vertical axis. In FIG. 2, reference numeral 71 denotes a cup body. Each processing unit 11 has the same configuration. In FIG. 2, the lifting pins 72 are not shown.

  As shown in FIG. 2, the cup body 71 is composed of roughly three members in this example. Specifically, the cup body 71 includes an inner cup 41 disposed so as to face the peripheral portion on the back surface side of the wafer W, an intermediate cup 42 disposed outside the inner cup 41, and an upper side of the intermediate cup 42. The outer cup 43 is laminated. The inner cup 41 is formed in a substantially ring shape so as to connect a position on the spin chuck 14 closer to the inner side than the outer peripheral end of the wafer W and a position outside the outer peripheral end in the circumferential direction. The ring body (guide part) 41a and a vertical wall 41b extending from the outer peripheral end of the ring body 41a downward in the circumferential direction. The upper surface of the ring body 41a is inclined downward as it goes from the central side toward the peripheral side, and has an inclined surface for dropping (flowing down) the resist solution shaken off from the outer peripheral portion of the wafer W by gravity. There is no. On the upper surface of the ring body 41a, a bevel cleaning nozzle 41c for discharging a solvent toward the peripheral portion on the back surface side of the wafer W is provided. The bevel cleaning nozzle 41c can be moved forward and backward in the radial direction of the wafer W. Has been placed.

  The intermediate cup 42 is a substantially annular member in which a recess for receiving the resist solution falling from the vertical wall 41b is formed in the circumferential direction. One end side of a drainage passage 45 for discharging the resist solution dropped from the vertical wall 41b is connected to a position substantially below the vertical wall 41b on the floor surface of the intermediate cup 42. The other end side of the drainage channel 45 is connected to a drainage unit (not shown).

  Then, on the bottom surface of the intermediate cup 42, at a position close to the side of the opening end of the drainage passage 45 (outside in the radial direction of the wafer W when viewed in a plane), as shown in FIG. In order to store the solvent, a substantially groove-shaped storage portion 61 having an upper surface opened is disposed so as to surround the wafer W in the circumferential direction. As will be described later, the storage portion 61 is for forming a solvent atmosphere in the outer peripheral portion of the wafer W when the resist film is dried. One end side of a solvent supply path (supply path) 62 is connected to the storage section 61, and the other end side of the solvent supply path 62 is connected to a solvent storage source 65 via a valve 63 and a flow rate adjustment section 64. It is connected. The valve 63 and the flow rate adjustment unit 64 constitute a solvent replenishment unit 111 described later.

  An exhaust port 46 for exhausting the processing atmosphere in which the wafer W is placed through the inside of the intermediate cup 42 is located at a position closer to the center side of the wafer W with respect to the opening end of the drainage passage 45 in the intermediate cup 42. Is formed. A separation wall 47 extending in the circumferential direction from the floor surface of the intermediate cup 42 to the upper side is provided between the opening end of the drainage passage 45 and the exhaust port 46. Gas-liquid separation is performed from the processing atmosphere. In other words, a base end side of an exhaust passage 31 to be described later is airtightly inserted into the intermediate cup 42 from the lower side, and a part of the wall surface of the exhaust passage 31 forms the separation wall 47. The exhaust ports 46 are formed, for example, at two locations so as to be separated from each other when seen in a plan view. The exhaust passage 31 extending from the exhaust port 46 will be described in detail later.

  The outer edge of the upper end side of the intermediate cup 42 extends upward and is bent inward to form a bent portion 42a. The tip of the bent portion 42a is the outer peripheral edge of the wafer W on the spin chuck 14. It is stretched horizontally so as to be close to. The height position of the horizontal surface on the upper end side in the bent portion 42a of the intermediate cup 42 and the height position of the surface of the wafer W in the spin chuck 14 are substantially the same height position. As shown in FIG. 2, a communication port 42 b is formed on the lower end side of the bent portion 42 a for communicating the atmosphere above and below the bent portion 42 a.

  As shown in FIG. 3, the communication port 42 b is formed so as to have a substantially elliptical shape when viewed in a plane, and is arranged at a plurality of positions along the circumferential direction at eight positions in this example at equal intervals. Yes. Therefore, when the wafer W is rotated around the vertical axis by the spin chuck 14, the resist solution or solvent shaken off from the peripheral edge of the wafer W and the air flow toward the outer peripheral portion of the wafer W due to the centrifugal force of the wafer W are already present. It enters the lower side of the bent portion 42a as an exhaust flow and flows toward the drainage passage 45 and the exhaust port 46 along the surface of the ring body 41a. Then, as will be described later, when the exhaust of the processing atmosphere is stopped (damper 48 is closed), the exhaust port 46 is closed so to speak, the gas atmosphere in the exhaust flow is volatilized by the solvent contained in the resist solution. Together with the generated volatile components, the wafer W goes around to the outer peripheral side of the wafer W through the communication port 42b.

  The two exhaust passages 31 extending from the exhaust port 46 described above are joined to each other on the downstream side of the intermediate cup 42, and as shown in FIG. Is connected to an exhaust duct 49 of the factory via a substantially plate-shaped damper (opening / closing body) 48 for performing opening / closing and flow rate adjustment. That is, as already described, the exhaust duct 49 is provided in common throughout the factory, and is configured to always form a constant amount of exhaust flow by an exhaust pump (not shown). In other words, the exhaust path 31 is assigned a part of the exhaust amount of the entire factory. An opening / closing mechanism is configured by the damper 48 and the exhaust path 31 provided with the damper 48. In FIG. 1, the exhaust duct 49 is partially cut away.

  Therefore, even if the above-described damper 48 is a case where the flow path in the exhaust path 31 is closed, as shown in FIG. 2, the other processing unit 11 or another semiconductor manufacturing apparatus is not adversely affected. (Or so that the adverse effect is minimized). That is, the exhaust path 31 in which the damper 48 is disposed has a substantially box shape as shown in FIG. 1, and an opening 51 is formed on the upper surface side, for example. As shown in FIG. 4A, the damper 48 hermetically closes the opening 51 and opens the flow passage in the exhaust passage 31, and as shown in FIG. It is configured such that it can be opened and closed between the position where the flow path is closed while being separated from the portion 51.

  Therefore, when the damper 48 closes the opening 51 as shown in FIG. 4A, the processing atmosphere in which the wafer W is placed is exhausted toward the exhaust duct 49 at a flow rate (first exhaust amount) V0, for example. When the damper 48 closes the flow path in the exhaust path 31 as shown in FIG. 4B, the exhaust of the processing atmosphere is stopped, while the atmosphere outside the coating apparatus (the atmosphere in the clean room or the processing unit 11 is The atmosphere in the coating and developing apparatus to be placed) is exhausted toward the exhaust duct 49 at a flow rate V0. That is, when the damper 48 is closed, the exhaust amount (second exhaust amount) exhausted from the processing atmosphere is adjusted to be smaller than the first exhaust amount described above, and specifically becomes zero.

  Further, as shown in FIG. 2 described above, at the position where the damper 48 interferes with the airflow flowing through the exhaust passage 31 (the position between the opening position and the closing position), the exhaust duct 49 includes The processing atmosphere and the external atmosphere flow in at flow rates Va and Vb, respectively. As described above, since the exhaust amount to be exhausted from each processing unit 11 is allocated in advance in the exhaust duct 49, the total value of the flow rate Va and the flow rate Vb becomes the flow rate V0. In other words, when the damper 48 is positioned so as to interfere with the air flow in the exhaust passage 31, the flow rate Va exhausted from the processing atmosphere to the exhaust duct 49 becomes smaller than the above-described flow rate V0, and this decrease (V0− The external atmosphere is drawn into the exhaust duct 49 by Va = Vb).

  Therefore, an exhaust flow having a substantially constant flow rate V0 flows into the exhaust duct 49 regardless of the position of the damper 48, so that it does not affect the other processing unit 11 and the semiconductor manufacturing apparatus. That is, when the opening 51 is not provided in the exhaust path 31 of the processing unit 11, when the exhaust is stopped by closing the flow path in the exhaust path 31 with the damper 48, the other processing unit 11 and the semiconductor manufacturing apparatus Then, the exhaust amount tends to increase by the amount of the processing unit 11 that stopped the exhaust. On the other hand, when the opening 51 is provided in the exhaust path 31, the exhaust gas having the flow rate V 0 assigned to the processing unit 11 flows toward the exhaust duct 49. Regarding the damper 48, FIG. 1 described above shows a state in which the rear damper 48 is opened and a state in which the front damper 48 is half open. In the following description, the state where the damper 48 is opened is referred to as “high exhaust”, and the state where the damper 48 is half open is referred to as “low exhaust”.

  As shown in FIG. 2 described above, the outer cup 43 extends upward from a position on the outer peripheral side of the communication port 42 b in the intermediate cup 42 and faces the outer peripheral end of the wafer W from the upper side. So that it bends. Above the outer cup 43, a fan unit 55 for forming a downflow air flow of clean gas in the processing atmosphere is disposed.

  As shown in FIGS. 1 and 5 described above, the coating apparatus described above is provided with a control unit 100 that outputs a control signal to the entire apparatus. The control unit 100 includes a storage unit 101 that stores a program configured to perform a resist film formation process, which will be described later, and controls the chemical solution supply device 110, the solvent replenishment unit 111, and the damper 48 described above. Is output, and a resist film having excellent uniformity in film thickness is formed on the surface of the wafer W. This program is installed in the control unit 100 from the storage unit 121 which is a storage medium such as a hard disk, a compact disk, a magneto-optical disk, a memory card, or a flexible disk. The program includes, for example, a process recipe that describes a procedure.

  Then, the effect | action of a coating device is demonstrated with reference to FIGS. First, the wafer W is placed on the spin chuck 14 and vacuum-sucked by the transfer arm (not shown) and the lift pins 72 described above (t0). In addition, the storage unit 61 is prefilled with a solvent, and for example, every time a set time elapses, the solvent is passed through the solvent replenishment path 62 so that the solvent does not run out due to volatilization. Replenish. On the bottom surface of the intermediate cup 42, the solvent quickly evaporates due to the room temperature atmosphere, and a solvent atmosphere is formed. In the processing atmosphere in which the wafer W is placed, a downflow airflow is formed by the fan unit 55, and this airflow is exhausted toward the exhaust path 31. Therefore, the solvent atmosphere generated from the storage unit 61 due to the volatilization of the solvent is exhausted together with the airflow. As shown in FIG. 6B, the damper 48 is positioned so as to interfere with the flow path in the exhaust path 31 (is in a half-open state). Accordingly, since the external atmosphere as well as the processing atmosphere flows into the exhaust duct 49, the state of exhaust in the processing atmosphere is low as shown in FIG. 6C.

  Next, the rotation of the spin chuck 14 is started, and as shown in FIG. 6A, the rotation speed of the spin chuck 14 is increased to, for example, 1500 rpm (t1), and also in FIGS. 6B and 6C. As shown, the damper 48 is fully opened to bring the processing atmosphere to a high exhaust state. Then, the nozzle 24 of the collective nozzle 1 is moved to a position facing the central portion of the wafer W, and the solvent is discharged from the nozzle 24 to perform a prewetting process. That is, the solvent discharged from the nozzle 24 collides with the central portion of the wafer W, and then spreads toward the outer peripheral portion of the wafer W to form a liquid film made of the solvent over the surface of the wafer W. At the same time, excess solvent is drained from the outer peripheral edge of the wafer W.

  The solvent drained from the outer peripheral edge of the wafer W falls to the bottom surface of the intermediate cup 42 through the region between the inner cup 41 and the intermediate cup 42, and then drains into the drainage passage 45 when a liquid pool is formed. Is done. In the solvent pool on the bottom surface of the intermediate cup 42, the solvent is volatilized by a normal temperature atmosphere where the processing unit 11 is placed to form a solvent atmosphere. Since the damper 48 is set to the fully open state as described above, the solvent atmosphere is exhausted to the exhaust path 31 together with the atmosphere above the wafer W and the solvent atmosphere generated from the storage unit 61.

  Subsequently, as shown in FIGS. 6A to 6C, the rotation speed of the spin chuck 14 is increased to the first rotation speed (for example, 2500 rpm) while the damper 48 is set to be fully open (t2). The resist solution is discharged toward the center of the wafer W. The resist solution is extended from the central side toward the peripheral side by the centrifugal force of the wafer W, and an excessive amount of liquid is drained from the outer peripheral edge of the wafer W as shown in FIG. The resist solution drained from the outer peripheral edge of the wafer W also falls to the bottom surface of the intermediate cup 42 through the region between the inner cup 41 and the intermediate cup 42. Since the resist solution contains the solvent as described above, a solvent atmosphere volatilized from the resist solution is formed in the intermediate cup 42, and the exhaust path 31 rides on the exhaust flow flowing from the processing atmosphere. Exhausted.

  Next, as shown in FIGS. 6A to 6C, the damper 48 is set to a low exhaust (half-open) state, and the rotation speed of the spin chuck 14 is reduced to a second rotation speed (for example, 100 rpm). (T3). After flattening the resist film on the surface of the wafer W in this way, the rotational speed of the spin chuck 14 is increased to, for example, 1500 rpm, and the damper 48 is closed (t4).

  On the surface of the wafer W, excess resist solution is further drained from the outer peripheral edge of the wafer W, and the flattening of the resist film further proceeds. Further, on the surface of the wafer W, the solvent is volatilized from the resist film, and a solvent atmosphere is formed. This solvent atmosphere spreads outward due to the centrifugal force of the wafer W, and flows into a region between the intermediate cup 42 and the inner cup 41. However, since the damper 48 is closed, the solvent atmosphere returns toward the outer peripheral edge of the wafer W through the communication port 42b in the intermediate cup 42 as shown in FIG.

  Further, the resist solution drained from the outer peripheral edge of the wafer W adheres to the bottom surface of the intermediate cup 42 or the ring body 41 a in the inner cup 41. Then, from the resist solution adhering to the intermediate cup 42 and the inner cup 41, the solvent is similarly volatilized to form a solvent atmosphere. This solvent atmosphere merges with the solvent atmosphere flowing from the processing atmosphere, and the communication port 42b is similarly formed. Get on the route of circulation. Similarly, the solvent atmosphere generated from the storage unit 61 flows toward the end of the wafer W through the communication port 42b.

  Here, as already described in detail, in the region facing the central portion of the wafer W, as shown in FIG. 9, a solvent atmosphere is formed by the solvent volatilized from the resist film, and therefore the resist in contact with the solvent atmosphere is formed. In the film, the solvent is less likely to evaporate (is difficult to dry). On the other hand, on the outer peripheral side of the wafer W, an atmospheric atmosphere (atmosphere containing no solvent) tends to flow from above the wafer W due to the centrifugal force of the wafer W. However, the damper 48 is closed so that the solvent atmosphere flows into the outer peripheral edge of the wafer W through the communication port 42b. Therefore, a solvent atmosphere is also formed in a region facing the outer peripheral edge of the wafer W, and the resist film is difficult to dry. Accordingly, the resist solution that flows from the central side to the peripheral side of the wafer W due to centrifugal force is quickly drained from the outer peripheral edge of the wafer W.

  In this way, the resist film on the surface of the wafer W has a uniform thickness over the entire surface, as can be seen from the examples described later. Specific numerical values of the film thickness are 30 nm to 15000 nm, and in this example, 7000 nm. Further, the difference (L1−L2) between the amount L1 of the resist solution discharged to the wafer W and the amount L2 of the resist solution remaining on the surface of the wafer W is to reduce the amount of the resist solution used as much as possible. In addition, it is almost zero, specifically 0.05 ml to 7.5 ml. When the relationship between the liquid amounts L1 and L2 is described by mathematical formulas, L2 = L1 × 120% to 1000%.

  Thereafter, the damper 48 is switched to a low exhaust state, and the number of rotations of the wafer W is increased so that the bevel cleaning nozzle 41c removes the resist film at the peripheral portion on the back surface side of the wafer W and discharges the solvent from the collective nozzle 1. The resist film at the peripheral edge on the front surface side of the wafer W is removed using the nozzle 24.

  According to the above-described embodiment, after the coating film made of the resist solution is formed on the surface of the wafer W, when the excess resist solution is dried while being shaken off, the damper 48 is closed to stop the exhaust of the processing atmosphere. doing. In addition, a storage portion 61 is provided on the bottom surface of the intermediate cup 42, and a solvent atmosphere is forcibly generated to flow through the peripheral portion of the wafer W. Therefore, a solvent atmosphere can be formed in the vicinity of the outer peripheral portion of the wafer W, so that the resist solution on the outer peripheral side of the wafer W can be prevented from being dried too much than the resist solution on the central side of the wafer W. Accordingly, when the central resist solution approaches the outer peripheral side due to centrifugal force, the resist solution can be discharged well from the outer peripheral end of the wafer W.

  That is, when the resist solution is dried while being shaken off, if the damper 48 is left open (unless the method of the present invention is employed), as shown in FIG. 10, a processing atmosphere is formed between the inner cup 41 and the intermediate cup 42. Therefore, a clean (solvent-free) atmosphere that flows from above the wafer W comes into contact with the outer peripheral side of the wafer W. Similarly, the solvent atmosphere generated from the resist solution or solvent pool on the bottom surface of the inner cup 41 is also exhausted without passing through the outer peripheral side of the wafer W. Therefore, on the outer peripheral side of the wafer W, the resist solution is easier to dry (the solvent is more likely to volatilize) than the central side. As the drying of the resist solution proceeds, the viscosity of the resist solution increases, so that it becomes difficult to flow. Therefore, even if the resist solution reaches the outer peripheral side by centrifugal force from the center side of the wafer W, it is difficult for the liquid to be drained from the outer peripheral edge of the wafer W, so that the resist solution is accumulated on the outer peripheral side. In other words, if the resist solution is dried with the damper 48 opened, the resist film becomes thicker on the peripheral side than on the central side of the wafer W. Therefore, it can be said that the present invention is a technique for satisfactorily discharging excess resist solution generated by the centrifugal force of the wafer W from the outer edge of the wafer W.

  Since the damper 48 is configured such that the external atmosphere flows into the exhaust duct 49 even if the exhaust of the processing atmosphere is closed as described above, the other processing section 11 and the semiconductor manufacturing apparatus are adversely affected. Is not necessary.

  Here, when the damper 48 is closed when the resist solution is dried, the damper 48 is configured to be openable and closable, and the processing atmosphere is exhausted during the discharge of the resist solution. Therefore, it can suppress that the other process part 11 adjacent, for example by the mist of a resist liquid is contaminated.

As described above, the greater the film thickness dimension of the resist film and the higher the viscosity of the resist solution, the less uniform the film thickness dimension. That is, when the resist film is formed so as to be a thick film, the height level of the resist film tends to vary over the surface. Further, the higher the viscosity of the resist solution, the more difficult the resist film flows. Therefore, the present invention is suitably used for a technique for forming a thick resist film using a high viscosity resist solution. These “high viscosity” and “thick film” mean specifically within the numerical ranges already described.
The exhaust amount zero includes the case where the flow rate Va is almost zero, and includes the case where the exhaust flow rate is less than 1.3 m ³ / min (the exhaust pressure of the exhaust port 46 is less than 25 Pa), for example.

In the example described above, the solvent atmosphere may be formed by a solvent or a resist solution that is shaken off from the peripheral edge of the wafer W without providing the storage portion 61. In this case, when the damper 48 is closed, the solvent volatilizes from the solvent or resist solution adhering to the surfaces of the inner cup 41 and the intermediate cup 42 to form a solvent atmosphere, and the resist film is dried at the peripheral edge of the wafer W. It is suppressed.
When the storage unit 61 is not provided in this way, before discharging the resist solution to the wafer W, for example, the solvent is discharged to a dummy wafer (dummy substrate) and the surface of the inner cup 41 or the intermediate cup 42 is also discharged. A solvent may be attached in advance. That is, as can be seen from the examples described later, even when the damper 48 is closed when the resist solution is dried, if the resist solution or solvent is not attached to the surface of the inner cup 41 or the intermediate cup 42, It is difficult to form a solvent atmosphere on the outer peripheral side of the wafer W. Therefore, the above-described solvent discharge process to the dummy wafer is a pre-process for forming a resist film on the product wafer W. Therefore, it can be said that the pre-wet processing described above corresponds to this pre-processing.

Hereinafter, another example of the present invention will be described with reference to FIG. FIG. 11 shows an example in which the storage unit 61 described above is arranged at a position facing the outer peripheral edge of the wafer W in the outer cup 43 instead of being provided on the bottom surface of the intermediate cup 42. In this example, the outer cup 43 has a vertical surface portion 131 formed so as to extend upward in the circumferential direction from a position on the outer peripheral side of the intermediate cup 42, and a peripheral edge of the wafer W from the upper end edge of the vertical surface portion 131. It is comprised by the inclined surface part 132 which inclines toward a part. Also in this example, the storage unit 61 is annularly provided over the entire circumference of the wafer W so as to surround the periphery of the wafer W. Therefore, the atmosphere drawn to the wafer W side by the centrifugal force of the wafer W flows along the inclined surface portion 132 toward the peripheral edge of the wafer W and along the inclined surface portion 132 as shown in FIG. The solvent atmosphere generated from the storage part 61 is involved at a midway position where the air flows through and reaches the peripheral part. Therefore, also in this example, the same effect as the above-described example can be obtained.
When providing the storage part 61 as described above, the above-described FIG. 2 and FIG. 11 may be combined. Specifically, the storage part is provided on both the tip of the outer cup 43 and the bottom surface of the inner cup 41. 61 may be arranged.
Therefore, the “position where the solvent vapor spreads” in the patent specification refers to the annular space between the inner cup 41 and the intermediate cup 42 and the lower side of the outer cup 43 from the bottom surface of the intermediate cup 42 through the communication hole 42b. At least one of the annular spaces (the space outside the intermediate cup 42). In other words, as described above, when the damper 48 is closed, the air flow goes back and forth (circulates) in the two annular spaces. By providing the storage portion 61 in at least one of the two annular spaces, It can be said that the storage unit 61 is “positioned at a position where the solvent vapor spreads”.

FIG. 13 shows an example in which a nozzle 141 serving as a discharge unit for discharging the solvent atmosphere is provided to the peripheral edge instead of providing the reservoir 61 when the solvent atmosphere is forcibly formed in the peripheral edge of the wafer W. Show. This nozzle 141 is arranged so that the opening end on one end side faces the outer peripheral end of the wafer W on the spin chuck 14, and the other end side is filled with a liquid solvent via a valve 142 and a flow rate adjusting unit 143. It is connected to the stored solvent generator 144. A supply pipe 145 for supplying an inert gas such as nitrogen gas is inserted on the upper surface of the solvent generating section 144, and the lower end of the supply pipe 145 is lower than the level of the solvent liquid level. Open on the lower side. Therefore, for example, by supplying an inert gas heated (warmed) to about normal temperature from the supply pipe 145 to the solvent generating unit 144, the fluorinated gas is bubbled inside the solvent, and the inert gas containing the solvent is contained. An atmosphere is formed at the peripheral edge of the wafer W.
When the solvent generator 144 is provided in this way, the lower surface side open end of the supply pipe 145 described above is positioned above the level of the liquid surface of the solvent, and the atmosphere at room temperature is applied to the liquid surface. Alternatively, a solvent atmosphere naturally evaporated in a normal temperature atmosphere may be supplied to the peripheral portion of the wafer W through the nozzle 41.

  The coating film formed on the wafer W by the method of the present invention may be an adhesive film made of a polyimide film or an adhesive instead of the resist film described above. Even in such a coating film, a coating solution obtained by diluting an organic material constituting the coating film with a solvent such as thinner is supplied to the wafer W, and similarly, drying is suppressed at the peripheral portion of the wafer W. Excess coating solution is drained.

  As described above, when the damper 48 is closed too early, the mist of the resist solution may flow into the processing atmosphere. On the other hand, when the delay is too late, the resist film on the outer peripheral side of the wafer W hardly flows (drying is difficult). Too much progress). Therefore, the timing is preferably set after the resist solution is completely discharged onto the wafer W until the resist solution is completely dried. Specifically, the timing t3 and the time t4 in FIG. Is a preset time.

(Experimental example 1)
Subsequently, an experiment conducted for confirming the effect of the present invention will be described. FIG. 14 shows the results of measuring the film thickness dimension in the diameter direction of the wafer W for the resist films obtained by the present invention and the conventional method, respectively. As can be seen from FIG. 14, in the related art, the outer edge portion of the wafer W is thicker than the central portion by 50 nm or more. On the other hand, in the present invention, the outer edge portion of the wafer W has the same thickness as that of the central portion.

(Experimental example 2)
In this experiment, after the resist solution and solvent adhering to the cups 41 to 43 are wiped off, a resist film forming process is continuously performed on the five wafers W by the method of the present invention, and then these five wafers are processed. The result of having measured the film thickness dimension of the resist film about W is shown. That is, when the resist solution is discharged to the first wafer W among these five wafers W, the resist solution and the solvent are not attached to the cups 41 to 43. On the other hand, for the second and subsequent wafers W, the resist solution adheres to the inner cup 41 and the intermediate cup 42 when the resist solution is discharged.

  As a result, as shown in FIG. 15, in the first wafer W, the film thickness dimension of the resist film at the outer peripheral edge of the wafer W is thicker than the center side, and the uniformity of the film thickness dimension is deteriorated. It was. On the other hand, the uniformity of the film thickness dimension is improved in the second and subsequent wafers W compared to the first wafer W. Therefore, when drying the resist solution, it can be said that it is preferable not only to close the damper 48 but also to attach a solvent to the cups 41 and 42 in advance. For this reason, it is preferable to perform pre-processing and pre-wetting processing using a dummy wafer as described above before performing the resist liquid discharge processing on the product wafer W. In FIG. 15, the first wafer W is indicated by a solid line, and the subsequent second and subsequent wafers W are indicated by broken lines.

W Wafer 11 Processing Unit 14 Spin Chuck 42b Communication Port 48 Damper 49 Exhaust Duct

Claims (12)

In an apparatus for forming a coating film by applying a coating liquid containing a solvent to a substrate, which is disposed in an atmosphere in which a downflow of clean gas is formed,
A substrate holding unit that holds the substrate horizontally and is rotatable about a vertical axis;
A coating liquid nozzle that discharges the coating liquid onto the surface of the substrate held by the substrate holding unit;
A cup body provided so as to surround the substrate held by the substrate holding portion;
An exhaust path for exhausting the internal atmosphere of the cup body;
When the coating liquid is applied by the rotation of the substrate, the exhaust path exhausts, and when the substrate rotates to dry the coating liquid on the substrate, the exhaust amount by the exhaust path is set to zero. And a control unit that outputs a control signal. The exhaust path is provided with an opening / closing mechanism for opening and closing the exhaust path,
The coating apparatus according to claim 1, wherein the control unit outputs a control signal for opening and closing the opening / closing mechanism to control an exhaust amount of the exhaust passage.   The opening / closing mechanism closes one of the flow path opening inside the cup body and the flow path opening outside the cup body, opens the other flow path, and opens one flow path. The coating apparatus according to claim 2, further comprising an opening / closing body that opens and closes between the position where the other channel is closed.   4. A solvent vapor supply unit for supplying a solvent vapor to a peripheral portion of the substrate when the substrate rotates in order to dry the coating liquid on the substrate. The coating apparatus as described in any one of these.   The coating apparatus according to claim 4, wherein the solvent vapor supply unit is a solvent storage unit provided in the cup body. The cup body extends outward and downward from a position facing the vicinity of the peripheral edge of the back surface of the substrate and is formed in an annular shape, and is provided so as to surround the substrate. An annular space between the inner cup that communicates with the exhaust passage, and an annular space that is provided so as to surround the inner cup from the outer side to the upper side of the inner cup, and is joined to the space on the lower side. An outer cup formed between the inner cup and
The said solvent storage part is provided in the position where solvent vapor | steam spreads in the said annular space inside an inner cup, and the said annular space outside an inner cup, The coating device of Claim 5 characterized by the above-mentioned.   The said solvent vapor supply part is a solvent storage part provided so that the opening part of the upper part of the said cup body might be enclosed, The coating device of Claim 4 characterized by the above-mentioned.   The controller rotates the substrate at a first rotational speed when the coating liquid is applied onto the substrate, and then rotates the substrate at a second rotational speed that is lower than the first rotational speed. In order to dry the substrate, a control signal is output so as to rotate at a higher rotational speed than the second rotational speed, and the coating liquid is applied at a set time after the substrate rotates at the second rotational speed. The coating apparatus according to any one of claims 1 to 7, wherein a control signal is output so that an exhaust amount is smaller than an exhaust amount at the time of the operation. In a method of forming a coating film by applying a coating liquid containing a solvent to a substrate in an atmosphere in which a clean downward airflow is formed,
Holding the substrate horizontally on the substrate holder;
A cup body is provided so as to surround the substrate while supplying the coating solution to the central portion of the substrate and rotating the substrate holding portion around the vertical axis to spread the coating solution on the substrate and apply the coating solution. Exhausting the internal atmosphere through the exhaust path;
And a step of rotating the substrate holding part to dry the coating liquid on the substrate in a state where the exhaust amount by the exhaust path is zero. The adjustment of the exhaust amount is performed by an opening / closing mechanism provided in the exhaust passage,
The opening / closing mechanism closes one of the flow path opening inside the cup body and the flow path opening outside the cup body, opens the other flow path, and opens one flow path. The coating method according to claim 9, further comprising an opening / closing body that opens and closes between the position where the other channel is closed.   11. The coating method according to claim 9, wherein when the substrate rotates to dry the coating solution on the substrate, a step of supplying a solvent vapor to a peripheral portion of the substrate is performed. A storage medium storing a computer program that runs on a computer,
A storage medium, wherein the computer program includes steps so as to implement the coating method according to any one of claims 9 to 11.

Images