JP2018069230A - Coating head and coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating head and a coating device capable of solving the problem of a spin coater while maintaining the advantage of the spin coater, namely, formation of a thin circular coating film with high accuracy.SOLUTION: A coating head 10 includes at least a liquid pool part 54 to enlargedly flow a supplied coating liquid in a coating width direction, and a linear nozzle 28 having a slit-shaped opening continuously formed in the liquid pool part 54. The coating head 10 for slit coat method is intended to form a circular coating film on a surface of a circular substrate 12 by discharging the coating liquid from the linear nozzle 28. The coating head 10 includes a coating width variable mechanism 44 by which a coating width of the coating liquid discharged from the linear nozzle 28 is made variable.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a coating head and a coating apparatus, and more particularly, to a coating head suitable for forming a thin circular coating film uniformly on the surface of a circular substrate (substrate to be coated) typified by a silicon wafer, and the coating head. The present invention relates to a coating apparatus.

  Various semiconductors, photosensors represented by CCDs, etc. (collectively referred to as electronic devices) are formed of various functional thin films, and are vacuum deposition methods represented by CVD (chemical vapor deposition). The manufacturing process has been structured around.

  However, since the CVD method needs to form a functional thin film in a vacuum environment, a large-scale vacuum chamber is required, and there are many problems in terms of price and production tact. In addition, in order to form a uniform thin film, the utilization efficiency of the target material for forming the film is poor, and there is a problem that the price of the electronic device cannot be reduced.

  In the manufacturing process of electronic devices, there is an increasing demand for film formation under normal atmospheric conditions, not under vacuum environment conditions. If this is realized, production tact will be improved and equipment costs will be reduced. Can be expected, and ultimately the price of electronic devices can be reduced.

  For this reason, many development studies have been made on film formation under a normal atmospheric environment, including application of advanced printing technology. However, only a spin coat method in which a photoresist material or an insulating film material is applied in a circle on the surface of a circular substrate of a silicon wafer has been put into practical use for forming a circular coating film.

  The spin coating method is a uniform thin film with a uniform thin film shape by spreading a coating solution from a nozzle near the center of a circular substrate and then rotating the circular substrate at a high speed to diffuse and spread the coating solution dropped by the centrifugal force of rotation. This is a method for obtaining a coating film. The greatest advantage of the spin coating method is that a highly accurate thin circular film can be obtained with a simple apparatus structure.

  As a coater / developer, the spin coating method has the largest production volume among semiconductor manufacturing apparatuses, but has several points to be improved. For this reason, the spin coating method is not satisfactory, but the fact is that there is no other alternative device and it must be used.

  The spin coating method coating apparatus has the following problems, for example.

  (1) A circular coating film is formed by fluidly diffusing the coating liquid dropped on the surface of the circular substrate held on the rotary table by centrifugal force accompanying the rotation of the rotary table. For this reason, the consumption of a coating liquid becomes 10-20 times the amount of coating liquid required for predetermined | prescribed thin film formation. In other words, the amount of the coating liquid that changes by a digit must be discarded in vain with respect to the amount of the coating liquid necessary for forming a thin coating film. Recently, even photoresist materials have become expensive, and it has been urgently required to improve the effective utilization efficiency of coating liquid (hereinafter referred to as “problem of effective utilization of coating liquid”).

  (2) Although it is related to (1) above, surplus coating liquid that has not adhered to the surface to be coated on the circular substrate is scattered to form mist particles. In many cases, the scattered mist particles accumulate on the outermost peripheral portion of the circular substrate to form a bulge, or adhere to the side surface portion of the substrate end that should not be originally attached. In the former case, the exposure process is adversely affected in the photoresist application. In the case of the latter adhesion, the production yield is greatly reduced due to contamination problems when handling the circular substrate. In order to eliminate these concerns, the present situation is that, after forming a thin film on a circular substrate, secondary processing called etching removal is required, called edge rinse. The implementation of this secondary processing is problematic from the viewpoint of reducing the price of electronic devices, and is a priority issue that must be improved (hereinafter referred to as “secondary processing for removing scattered coating liquid”). Therefore, when a circular coating film is formed on the surface of the circular substrate, it is desirable that the circular coating film can be formed in the same shape as the circular substrate, for example, so as not to protrude from the application target surface of the circular substrate.

  (3) Further, since the spin coating method requires the rotation of the circular substrate, the rotation is increased from the initial speed of 0 to reach a predetermined rotation speed, and after maintaining that speed, the rotation is decelerated and the speed of 0 is reached. Will return. That is, in the single-wafer coating process for a circular substrate, since a coating time from the start of rotation to the end of rotation is required for each circular substrate, there is a problem that the production tact time becomes long. Increasing the rotation speed can shorten the production tact time, but the holding force of the rotary table that holds the circular substrate is limited, so the speed of rotation is also limited. Even if the speed level can be increased, the speed of acceleration / deceleration is increased, which is not very effective for shortening the tact time. In addition to the secondary processing time described above, shortening the production tact time is also an important issue (hereinafter referred to as “problem with long production tact time”).

  (4) Recently, in the application of a circular substrate, the film thickness needs to be appropriate as in the case of forming an insulating film, but there is also a great demand for applying a high-viscosity coating liquid with a relatively high viscosity of the coating liquid. However, since the spin coating method is premised on large-scale fluid diffusion, it is difficult to apply it in the case of a high-viscosity coating liquid (hereinafter referred to as “the problem of non-application of a high-viscosity coating liquid”).

  Regarding the various problems of the spin coating method described above, since there is no effective method to replace the spin coating method, although there is a recognition as a problem, there is a situation where the problem solution is shelved. After all, since the spin coating method forms a circular coating film by means of rotation, the above problems (1) to (4) arise, and it is effective to add a supplementary function to the spin coating method. Is not a good solution.

  By the way, as a precise coating device, a slit that forms a uniform coating film by moving a coating head or a substrate while discharging a fixed amount of coating liquid from a slit-like linear nozzle having a certain length. There are a coating method and a roll coater method in which a thin coating film is formed through a substrate between a pair of rolls impregnated with a coating solution.

  However, all are premised on forming a rectangular coating film on a rectangular substrate, and do not correspond to forming a circular coating film on a circular substrate.

  Furthermore, there have been a few proposals for coating methods intended to solve the above-mentioned problems by combining the coating technology of the slit coating method and the coating technology of the spin coating method. For example, as described in Patent Document 1, an invention has been disclosed in which a thin film is applied while moving a single nozzle in a spiral on a circular substrate.

The invention described in Patent Document 2 is a method of performing coating in two stages. First, a plurality of coating heads are set so that the nozzles come in the circumferential direction, and the first coating is performed at a coating speed. Accordingly, after discharging the coating solution, the coating solution is flattened by high-speed rotation by a second spin coater.
The intention of using a plurality of slit coaters to handle the dripping nozzles in a spin coater is not understandable from the viewpoint of material saving, but it is not a solution to many problems inherent in spin coaters and the cost of the equipment is low. It will be very expensive. Patent Document 3 is also the same invention as Patent Document 2.

JP 2005-305440 A JP 2000-301043 A JP-A-11-239754

  However, the method of Patent Document 1 can realize thin film coating with a simple configuration and can minimize the amount of coating liquid used. However, it takes time to coat and whether the formed film thickness characteristic is uniform. I doubt. In addition, in the methods of Patent Document 2 and Patent Document 3, the intention of using a plurality of slit coaters to correspond to the portion of the dropping nozzle in the spin coater is not understandable from the viewpoint of material saving, but there are many inherently possessed by the spin coater. This is not a solution to this problem, and the price of the equipment becomes very high.

  As described above, a coating apparatus that forms a uniform thin-film circular coating on the surface of a circular substrate such as a silicon wafer is not satisfactory with respect to any of the above.

  Against this background, the spin coater has a completely new concept that can solve the above-mentioned problems (1) to (4) while maintaining the advantage of forming a highly accurate thin circular coating film. There is a need for a coating apparatus.

  In addition, the new concept coating device is not a dedicated device for circular coatings, but is a convenient coating device that can form coatings with shapes other than circular coatings such as rectangular coatings on substrates and roll films. Is desirable.

  The present invention has been made in view of such circumstances, while maintaining the advantage of forming a highly accurate thin circular coating film that the spin coater has, `` problem of effective use of coating solution '' that the spin coater has. , Providing a coating head and a coating device that can solve all of the "secondary processing problem of scattering coating solution removal", "problem with long production tact time", and "problem of non-application of high viscosity coating solution" The purpose is to do.

  In order to achieve the above-mentioned object, a coating head according to the present invention has a linear shape having a liquid reservoir that spreads the supplied coating liquid in the coating width direction, and a slit-like opening continuously formed in the liquid reservoir. In a slit coating method coating head that includes at least a nozzle and forms a coating film on the surface of a substrate to be coated by discharging the coating liquid from the linear nozzle, the coating width of the coating liquid discharged from the linear nozzle is varied. A variable coating width mechanism is provided.

  As an aspect of the coating head, the coating width variable mechanism includes a pair of plate-shaped sealing members that are fitted in the slit-shaped openings of the linear nozzles so as to be movable in the coating width direction and seal the fitted openings. Preferably, the seal member moving means is configured to at least open and close the opening of the linear nozzle by moving the pair of seal members away and close in the application width direction.

  As an aspect of the coating head, it is preferable that the plate-like sealing member is formed in a bent structure in which a thin metal plate is bent into a V shape, and the V-shaped portion is fitted into the linear nozzle.

  The plate-like seal member is formed by laminating a plurality of thin metal plates of different lengths in a laminated structure, the thick part is supported by the seal member moving means, and the thin part is fitted to the linear nozzle. It is preferable to be inserted.

  As an aspect of the application head, the seal member moving means includes a pair of moving blocks provided in the application width direction of the liquid reservoir, and a right screw and a left screw with a central portion in the application width direction as a boundary. It is preferable to include a ball screw that penetrates the moving block into a right screw and a left screw and a servo motor that rotates the ball screw.

  As an aspect of the coating head, the seal member moving means is provided in close contact with the liquid reservoir at the lower part of both ends of the liquid reservoir in the coating width direction, and a dovetail groove is formed in the upper surface of the central portion in the coating width direction. The dovetail block is formed at the lower end of the pair of moving blocks, and the dovetail block is slidably mated with the dovetail groove. It is preferable to further have a joint portion.

  As an aspect of the coating head, the coating width variable mechanism is a pair of columnar types that are movably fitted in a coating width direction of a liquid reservoir formed as a hollow portion having a cylindrical hole shape and seal the fitted cavity. A linear nozzle that is at least composed of a sealing member and a sealing member moving means that moves the pair of cylindrical sealing members apart and moves in the application width direction, and is continuous with the liquid reservoir by the movement of the pair of cylindrical sealing members It is preferable to vary the coating width by opening and closing the opening entrance of the coating.

  In order to achieve the above object, a coating apparatus according to the present invention supplies a coating liquid to a liquid reservoir portion of a coating head by a constant flow rate supply pump, and has a slit-like opening continuously formed in the liquid reservoir portion. While discharging the coating liquid from the nozzle-like nozzle to the substrate to be coated, relatively moving at least one of the coating head and the substrate to be coated in a direction orthogonal to the coating width direction of the linear nozzle, In a slit coat method coating apparatus for forming a coating film on a surface of a substrate, an X-axis moving mechanism for relatively moving at least one of a coating head having a coating width variable mechanism and a coating head and a substrate to be coated A Z-axis movement mechanism that adjusts the gap between the discharge port of the linear nozzle of the coating head and the surface of the substrate to be coated, and a control unit that controls at least the coating width variable mechanism, the X-axis movement mechanism, and the Z-axis movement mechanism When Characterized by comprising a.

  As an aspect of the coating apparatus, the control unit controls the coating width variable mechanism and the X-axis movement mechanism, and the opening / closing speed at which the pair of seal members open and close the opening of the linear nozzle and the substrate to be coated during the coating process time. It is preferable to form a circular coating film on the substrate to be coated by synchronizing the moving speed of the film.

  As an aspect of the coating apparatus, the control unit sets the opening / closing speed at the start and end of application of the pair of seal members to 0 (zero) and the opening / closing speed pattern of the opening / closing speed during the coating process time to be a sine wave pattern On the other hand, it is preferable that the circular coating film is formed by changing the movement speed pattern of the movement speed of the substrate to be coated to a sine wave pattern delayed by ¼ cycle (phase difference 90 degrees) from the opening / closing speed pattern.

  As an aspect of the coating apparatus, the coating head is provided with a pressure sensor for detecting the internal pressure of the coating head, and the coating process time from the start of coating to the end of coating obtained by a preliminary test for forming a circular coating film on the substrate to be coated The relationship between the ideal pressure pattern of the internal pressure of the coating head according to the opening and closing operation of the linear nozzle and the discharge amount pattern from the coating head is input to the control unit, and the control unit detects the value of the pressure sensor during the coating process time It is preferable to vary the discharge amount of the coating liquid from the coating head by controlling the rotation speed of the supply pump so that the difference between the value and the set value of the ideal pressure pattern becomes zero.

  As an aspect of the coating apparatus, the control unit controls the coating width variable mechanism before starting coating and sets the predetermined coating width to stop the control of the coating width variable mechanism and start coating to start the surface of the substrate to be coated. It is preferable to form a rectangular coating film.

  According to the present invention, while maintaining the advantage of forming a high-precision thin circular coating film possessed by a spin coater, the problem of effective use efficiency of the coating liquid possessed by the spin coater, and the secondary processing of removing the scattered coating liquid All of “Problem”, “Problem with long production tact time”, and “Problem of non-application of high viscosity coating liquid” can be solved.

The perspective view which shows the external appearance of the coating device of this invention 1 is an exploded view, an assembly view, and a cross-sectional view of a casing of a coating head according to a first embodiment of the present invention. Assembly drawing and exploded view of the conventional slit coating method housing Exploded view showing a coating width variable mechanism in the coating head of the present invention Explanatory drawing explaining the opening / closing operation | movement of the sealing member in the coating head of this invention Sectional drawing of the X-axis direction of the coating head of this invention The perspective view of the plate-shaped sealing member of the coating head of the present invention The exploded view of the housing | casing of the coating head of the 2nd Embodiment of this invention Sectional drawing of the X-axis direction of the coating head of the 2nd Embodiment of this invention The perspective view of another aspect of the plate-shaped sealing member of the coating head of this invention Explanatory drawing of the coating head of the 3rd Embodiment of this invention Comparison diagram with the coating head of the third embodiment of the present invention The graph which shows the relationship between the discharge amount from the coating head in the coating device of this invention, the internal pressure of a coating head, and the rotational speed of a supply pump. Explanatory drawing explaining the opening / closing speed pattern of the sealing member during the coating process time and the moving speed pattern of the circular substrate Explanatory drawing explaining the application width change of a linear nozzle and the moving speed of a circular substrate when forming a circular coating film of the same size on a circular substrate Explanatory drawing explaining another aspect of the opening / closing speed pattern of the sealing member during the coating process time and the moving speed pattern of the circular substrate Explanatory drawing explaining another aspect of the discharge amount pattern from the coating head during the coating process time, and the moving speed pattern of the circular substrate

  Preferred embodiments of a coating head according to the present invention and a coating apparatus provided with the coating head will be described in detail below with reference to the accompanying drawings.

[Overall configuration of coating equipment]
The coating apparatus according to the embodiment of the present invention includes at least a liquid reservoir that spreads the supplied coating liquid in the coating width direction, and a linear nozzle that has a slit-like opening continuously formed in the liquid reservoir. In the coating head of the slit coating method that forms a coating film on the surface of the substrate to be coated by discharging the coating liquid from the linear nozzle, a coating width variable mechanism that varies the coating width of the coating liquid discharged from the linear nozzle By providing, a circular coating film can be formed on the surface of the circular substrate.

  Note that the coating apparatus according to the embodiment of the present invention is not limited to forming a circular coating film on the surface of a circular substrate, but can form coating films of various shapes, but in this embodiment, it is represented by a silicon wafer. An example in which a circular coating film having the same size as the circular substrate is formed on the surface of the circular substrate (substrate to be coated) so as not to protrude from the circular substrate will be described below.

  FIG. 1 is a perspective view showing the external appearance of the overall configuration of a coating apparatus 10 according to an embodiment of the present invention.

  As shown in FIG. 1, the coating device 10 is housed in a casing 14 that can be opened and closed so that dust and the like do not adhere to the circular substrate 12 and the coating film. The casing 14 includes a base chamber 14A in the lower part and a coating chamber 14B in the upper part.

  A substrate table 16 for adsorbing and fixing the circular substrate 12 is disposed at a substantially central position of the coating chamber 14B, and a coating head 18 is disposed above the substrate table 16. In the present embodiment, the method of fixing the circular substrate 12 with the substrate table 16 will be described by suction fixation, but is not limited to this.

  Here, the X-axis direction shown in FIG. 1 indicates the moving direction of the circular substrate 12, the Y-axis direction indicates the coating width direction of the coating head 18, and the Z-axis direction indicates the vertical direction of the coating head 18. In this embodiment, in order to simplify the explanation, the coating head 18 is fixed, and the circular substrate 12 is perpendicular to the coating width direction (Y-axis direction) of the coating head 18 (X-axis direction). The case of moving will be described. However, the circular substrate 12 may be fixed and the coating head 18 may be moved in the X axis direction.

  The coating head 18 is supported by a portal-shaped gantry structure 20 for supporting a coating head. The gantry structure 20 is equipped with a Y-axis movement mechanism 22 that moves the coating head 18 in the Y-axis direction, and a Z-axis movement mechanism 24 that moves the coating head 18 in the Z-axis direction.

  Control of the Y-axis moving mechanism 22 and the Z-axis moving mechanism 24 is controlled by a command from a control unit 26 provided inside the base chamber 14A. The control unit 26 controls the Y-axis moving mechanism 22 to move the coating head 18 in the Y-axis direction, thereby positioning the coating head 18 and the circular substrate 12 fixed to the substrate table 16 in the Y-axis direction. . Note that the Y-axis moving mechanism 22 is not necessarily required when it is previously positioned in the Y-axis direction.

  In addition, the control unit 26 controls the Z-axis moving mechanism 24 to move the coating head 18 up and down, whereby a slit-like linear nozzle 28 that discharges the coating liquid from the coating head 18 (see FIG. 2C). The application gap (also referred to as clearance), which is a gap between the discharge port 28A and the surface of the circular substrate 12, is adjusted.

  In the vicinity of the coating head 18, a coating liquid tank 33 for storing the coating liquid is disposed and connected to the coating head 18 via a supply pump 30 (constant flow pump) and a liquid feed pipe 32. As the supply pump 30, a reciprocating pump or a rotary pump can be preferably used. Of these, reciprocating pumps often have a single direction of liquid delivery, and when performing precise flow control for the purpose of feedback control, etc., a rotary pump capable of bidirectional liquid delivery is preferred. Is easy to deal with.

  In the present embodiment, the supply pump 30 is driven by a servo motor 34 for driving the supply pump, and by controlling the rotation speed of the supply pump 30, the coating liquid fed from the coating liquid tank 33 to the coating head 18. The coating liquid flow rate was variably controlled with high accuracy. It is also preferable to add a speed reduction mechanism to improve control resolution. The detailed structure of the coating head 18 will be described later.

  On the other hand, the substrate table 16 is mounted on the X-axis moving mechanism 36 and configured to be movable in the X-axis direction. The X axis moving mechanism 36 is controlled by the control unit 26. As the X-axis moving mechanism 36, the substrate table 16 is mounted on an X-axis slider 36B slidably supported on a rail 36A laid in the X-axis direction, and the X-axis slider 36B is slid by a ball screw (not shown). The structure to be made can be adopted. The ball screw is configured to move at an arbitrary slide speed by being driven by a servo motor (not shown) for controlling the movement of the substrate table.

  Usually, in a silicon wafer or the like, an orientation flat or a notch is formed on the outermost peripheral portion of the circular substrate 12 in order to determine the orientation of the circular substrate 12. Therefore, the substrate table 16 is provided with a rotating mechanism 38 for positioning the orientation flat or notched circular substrate 12 in the circumferential direction so that the positioning can be performed before the start of coating. The rotation mechanism 38 is only a role of a positioning mechanism, and only determines a position of the circular substrate 12 by an optical method. Like the spin coater, the rotation of the substrate table 16 is performed on the circular substrate 12. The coating liquid is not fluidly diffused.

  Further, with respect to the attachment / detachment of the circular substrate 12 from the substrate table 16, a substrate attachment / detachment groove is formed in the substrate table 16. The circular substrate 12 is sucked and fixed to the substrate table 16 by being sucked by the substrate suction vacuum pump 40 installed outside the casing 14. After the application is completed, the suction of the vacuum pump 40 is released, and the circular substrate 12 is detached from the substrate table 16 by the lift pin mechanism 43 for taking out the substrate attached to the substrate table 16.

  In the base chamber 14 </ b> A in the lower part of the casing 14, the above-described control unit 26 that controls the operation of the entire coating apparatus 10 is provided. As the control unit 26, a sequencer (PLC: Programmable Logic Controller) can be suitably used. Further, the coating apparatus 10 is provided with a man-machine interface touch panel 42 for setting parameters of film forming conditions.

  Next, the coating head 18 mounted on the coating apparatus 10 will be described.

[First embodiment of coating head]
FIG. 2A is an exploded view showing the appearance of the casing portion of the coating head 18 of the present invention. 2B is an assembly view of FIG. 2A, and FIG. 2C is a cross-sectional view taken along the line aa of FIG. 2B. Further, FIG. 2 does not show the application width varying mechanism 44 (see FIG. 4).

  As shown in FIG. 2, the casing 46 of the coating head 18 has a thin metal spacer shim 48 (48A, 48B) sandwiched between two thick metal plates consisting of a chamber plate 46A and a blocking plate 46B. It has a structure. As a result, a liquid reservoir 54 that spreads the supplied coating liquid in the application width direction (Y-axis direction) and a linear nozzle 28 that has a slit-like opening continuously formed in the liquid reservoir 54 are formed. The

  A plurality of connecting holes 50 are formed in the chamber plate 46A, the blocking plate 46B, and the spacer shim 48, and the chamber plate 46A, the blocking plate 46B, and the spacer shim 48 are integrally connected and fixed by bolts (not shown). Thereby, as shown to (B) of FIG. 2, the housing | casing part of the coating head 18 is assembled. On both side surfaces of the assembled coating head 18, cylindrical holes 52 for the coating width varying mechanism 44 described later are formed.

  The chamber plate 46A is formed with a liquid reservoir 54 that stably stores the coating liquid supplied to the coating head 18 from the supply pump 30 (see FIG. 1) via the liquid feeding pipe 32. The liquid reservoir portion 54 is formed as a hollow portion having, for example, a rectangular tube shape or a cylindrical shape that is long in the coating width direction of the coating head 18. In addition, it is preferable to form an air vent 56 in the coating head 18 that draws out air from the liquid reservoir 54 when the coating solution is fed.

  The spacer shim 48 includes an upper spacer shim 48A that is sandwiched above the liquid reservoir 54 and a pair of L-shaped lower spacer shims 48B and 48B that are respectively sandwiched at both lower ends of the liquid reservoir 54. Composed.

  Then, by sandwiching and fixing a thin metal spacer shim 48 between the chamber plate 46A and the blocking plate 46B, as shown in FIG. 2C, the lower part of the coating head 18 (the liquid reservoir 54). The linear nozzle 28 having a narrow slit-like opening that continues from the liquid reservoir 54 is formed. The chamber plate 46A is formed with a coating liquid supply through-hole penetrating from the back surface to the liquid reservoir 54, and a liquid feed pipe for supplying the coating liquid from the supply pump 30 to the coating head 18 in the through-hole. One end of 32 is connected.

  As a result, the coating liquid supplied from the supply pump 30 to the liquid reservoir 54 of the coating head 18 is spread in the coating width direction by the liquid reservoir 54, and forms a quantitative parallel flow in the linear nozzle 28. . Then, the ink is discharged from the discharge port 28 </ b> A (opening tip) of the linear nozzle 28 onto the surface of the circular substrate 12.

  Further, the application head 18 is provided with a pressure sensor 31 that monitors a change in the internal pressure of the liquid reservoir 54 during the application process time from the application start to the application end. As shown in FIG. 2, the chamber plate 46 </ b> A is formed with a through hole 35 that penetrates from the side surface of the chamber plate 46 </ b> A to the liquid reservoir 54. The sensor portion 31 </ b> A of the pressure sensor 31 that detects the internal pressure of the coating head 18 is fixed to the through hole 35 so as to face the liquid reservoir 54. Thereby, the pressure sensor 31 detects the pressure fluctuation of the internal pressure of the coating head 18 (the fluid pressure of the liquid reservoir 54) of the coating liquid supplied from the supply pump 30 to the coating head 18. The detection value detected by the pressure sensor 31 is sequentially sent to the control unit 26.

  The position at which the sensor portion 31A of the pressure sensor 31 faces the liquid reservoir 54 is the central position of the liquid reservoir 54 in the application width direction and the inlet of the linear nozzle 28 (continuous to the discharge port 28A). The position in the vicinity of the opposite side) is preferred. This is because there is a close relationship between the internal pressure detected at this position and the discharge amount of the coating liquid discharged from the linear nozzle 28.

  When it is necessary to change the discharge amount from the coating head 18 at each cross section in the radial direction of the coating film like a circular coating film, the coating control system using the pressure sensor 31 plays an important role. . In other words, by utilizing the close relationship between the internal pressure of the coating head 18 and the variation in the discharge amount corresponding to the variation in the coating width of the linear nozzle 28, the circular substrate 12 has a uniform film thickness. An application control system capable of obtaining a circular coating film can be constructed.

  That is, by detecting the internal pressure of the coating head 18 with the pressure sensor 31, the discharge amount of the coating liquid corresponding to the opening length (coating width) of the linear nozzle 28 in the Y-axis direction is calculated. Then, the rotational speed of the supply pump 30 is increased / decreased so as to obtain the internal pressure of the coating head 18 necessary to ensure the calculated discharge amount, and the liquid feeding amount of the coating liquid fed to the coating head 18 is increased / decreased. Thus, a circular coating film having a uniform film thickness can be obtained with high accuracy.

  The pressure sensor 31 may be any sensor that can appropriately take a response according to the flow of the viscous fluid, such as a coating liquid. Regarding the response speed, those that can respond to a very high-speed response are likely to carry noise, and in many cases, additional means such as a filter are required for nozzle removal, and appropriate selection is important. Therefore, a semiconductor type or resistance wire strain gauge type pressure sensor 31 can be suitably used. The coating control system will be described in detail later.

  Here, the essential difference between the coating head 18 of the present embodiment and the conventional coating head 1 in the slit coating method will be described.

  3A and 3B are an assembled view (A) and an exploded view (B) showing the appearance of the casing portion of the coating head 1 of the conventional slit coating method. As can be seen from FIG. 3, the conventional coating head 1 is configured by sandwiching one spacer shim 3 made of a thin metal between the chamber plate 2A and the blocking plate 2B, and the opening shown in FIG. The length T becomes the coating width. In FIG. 3, reference numeral 4 denotes a liquid reservoir, and reference numeral 5 denotes a coating solution feeding pipe.

  Therefore, in the conventional coating head 1, when the circular substrate 12 is relatively moved in the direction orthogonal to the coating width direction of the coating head 1 while the coating liquid is discharged from the linear nozzle, a rectangular coating film is formed. . This makes it impossible to form a circular coating film on the circular substrate 12 such as a silicon wafer.

  Therefore, in the coating head 18 according to the embodiment of the present invention, in order to form a circular coating film on the circular substrate 12, the linear nozzle 28 moves in the Y-axis direction as the circular substrate 12 moves in the X-axis direction. A coating width varying mechanism 44 that can vary the coating width that is the opening length is provided.

  Assuming that the moving direction of the circular substrate 12 is the X-axis direction and the variable application width direction of the linear nozzle 28 of the application head 18 is the Y-axis direction, the variable application width of the X-axis direction moving application head 18 of the circular substrate 12 is synchronized. This shows that a circular coating film can be drawn on the circular substrate 6. This is similar to drawing a combined Lissajous waveform by inputting an arbitrary voltage waveform to each of the X axis and the Y axis on the oscilloscope screen as a similar phenomenon.

  That is, the coating head 18 according to the embodiment of the present invention is provided with the coating width variable mechanism 44 that varies the coating width, and the control unit 26 includes the coating width variable mechanism 44 and the X-axis moving mechanism 36 that moves the circular substrate 12. Is different from the conventional coating head 1 in that a circular coating film can be formed on the surface of the circular substrate 12 by controlling in accordance with the above.

  Next, the coating width variable mechanism 44 that varies the coating width in the coating head 18 according to the embodiment of the present invention will be described.

(Application width variable mechanism of application head)
As shown in FIG. 4, the coating width varying mechanism 44 provided in the coating head 18 of the present invention is fitted and fitted in a linear nozzle 28 having a slit-like opening so as to be movable in the coating width direction. A pair of plate-like seal members 58, 58 that seal the opened portion, and a seal member movement that opens and closes the opening of the linear nozzle 28 by moving the pair of seal members 58, 58 apart and close in the coating width direction. And means 60 at least. In FIG. 4, the pressure sensor 31 is not shown.

  The width W1 of the seal member 58 is formed to be the same as the length W2 of the pair of L-shaped lower spacer shims 48B sandwiched between the lower ends of the liquid reservoir 54. When the pair of seal members 58, 58 are separated to the maximum by the seal member moving means 60, the seal members 58, 58 are the seal member storage portions of the linear nozzle 28 formed by the pair of lower spacer shims 48B, 48B. 62 and 62, respectively. Therefore, the maximum coating width L is between the pair of L-shaped lower spacer shims 48B and 48B.

  A ball screw 64 is disposed penetrating in the longitudinal direction of the liquid reservoir 54 of the coating head 18, that is, in the coating width direction (Y-axis direction). Both end portions of the ball screw 64 protrude from the cylindrical hole 52 on the side surface of the coating head 18 and are rotatably supported by ball screw shaft bearings 66, 66 provided in the cylindrical hole 52. A shaft seal member 69 is interposed between the cylindrical hole 52 and the bearing 66 so that the coating liquid in the liquid reservoir 54 does not leak from the cylindrical hole 52.

  The ball screw 64 is made into a right screw and a left screw with a central portion as a boundary, and a pair of moving blocks 68 and 68 including a rotation stopper are screwed to the ball screw 64 (see FIG. 6). That is, of the pair of moving blocks 68, 68, one moving block 68 is screwed to the right screw of the ball screw 64, and the other moving block 68 is screwed to the left screw of the ball screw 64.

  Then, the seal member holding block 70 is fixed to the lower end surface of each moving block 68, and the upper end portion of the above-described seal member 58 is fixed to the lower surface of the seal member holding block 70 (see FIG. 6). Thereby, with the rotation of the ball screw 64, the moving block 68, the seal member holding block 70, and the seal member 58 move together.

  One end of the ball screw 64 is connected to a servo motor 74 mounted on the coating head 18 via a plurality of gears 72, and the servo motor 74 is connected to the control unit 26 by a signal cable or wirelessly. Accordingly, the circular substrate 12 is circularly moved on the surface of the circular substrate 12 by a combination of the movement of the circular substrate 12 by the X-axis moving mechanism 36 and the separation movement and approaching movement of the seal members 58 by the coating width variable mechanism 44 provided in the coating head 18. A coating film can be formed.

  FIG. 5 is a view of the linear nozzle 28 of the coating head 18 as viewed from the front end side of the opening. FIG. 5A shows a pair of seal members 58 and 58 approaching each other in the coating width direction (Y-axis direction). In the contacted state, (B) is a state in which the pair of seal members 58 and 58 are separated to the maximum in the coating width direction. As can be seen from FIG. 5, the pair of seal members 58, 58 can be moved apart and approached to perform an opening / closing operation for opening and closing the opening of the linear nozzle 28 in the coating width direction.

  Particularly important in the coating head 18 is a coating width variable mechanism 44, which varies the opening length of the linear nozzle 28 at a controlled opening / closing speed (synonymous with the moving speed) to track the circular coating film. It is necessary to simultaneously play the role of varying the original coating width for drawing and the role of a seal for preventing liquid leakage from the casing portion of the coating head 18.

  A general sealing method is required to fill a gap that causes liquid leakage between members. However, when the seal member 58 moves as in the case of the application head 18 according to the embodiment of the present invention, the seal member 58 is pressed against the seal surface with which the seal member 58 contacts with sufficient surface pressure. It is necessary to seal.

  FIG. 6 is a cross-sectional view in the X-axis direction of the coating head 18 assembled from the exploded view of FIG. 4, mainly illustrating a seal structure for preventing liquid leakage of the coating width varying mechanism 44.

  As shown in FIG. 6, the seal surface 28B has a very narrow gap (usually a slit) between the linear nozzles 28 formed between the chamber plate 46A and the blocking plate 46B constituting the casing portion of the coating head 18. It is a wall surface (refer to (C) in FIG. 2) of the opposite surfaces of the gap.

  As shown in FIG. 7, the plate-like seal member 58 has a bent structure in which a metal thin plate is bent into a V shape, and is inserted into a gap between the linear nozzles 28. 58A and fixing portions 58B and 58B that extend horizontally from the insertion portion 58A to the left and right and are fixed to the lower surface of the seal member holding block 70.

  The material of the seal member 58 may be any material as long as it is a thin plate that is not easily distorted and has elasticity. For example, spring steel can be suitably used.

  As described above, the sealing member 58 has a bent structure that is bent in a V-shape, so that the elastic effect of returning to the original state is always exhibited. Therefore, when the V-shaped insertion portion 58A of the seal member 58 is inserted into the narrow gap of the linear nozzle 28, the insertion portion 58A tries to expand, and the wall surface (seal surfaces 28B, 28B) of the linear nozzle 28 is expanded. It will press with a fixed surface pressure and can exhibit the outstanding sealing performance.

  Further, regarding the movement of the seal member 58, since the direction in which the frictional force is applied is nearly perpendicular to the movement direction, the influence on the accuracy of the opening / closing speed of the seal member 58 is extremely small. Further, the thickness of the seal member 58 formed of a metal thin plate is uniquely determined by the film thickness of the coating film, and needs to be changed according to the required specifications. In some cases, when the metal thin plate is further folded and the V shape is laminated in order to increase the thickness, an elastic effect is further generated in the laminated portion. Furthermore, a structure in which an adhesive having an elastic effect is sandwiched between folded thin plates is also effective.

  By the way, ensuring the surface pressure on the wall surfaces (seal surfaces 28B, 28B) of the linear nozzle 28 by the seal member 58 and ensuring the accuracy of the opening / closing speed of the seal member 58 are contradictory events. Therefore, it is important to secure a seal surface that does not affect the opening / closing speed of the seal member 58. In other words, the selection of the seal surface that can prevent the ball screw 64 that moves the seal member 58 from being deformed as much as possible due to the surface pressure, the structure and material of the seal member 58, and the design of the moving structure that moves the seal member 58. Become important.

  Further, when the application width of the linear nozzle 28 is varied by moving the pair of seal members 58, 58 apart and close, the seal is caused by frictional resistance due to surface pressure against the wall surface (seal surface 28B) of the linear nozzle 28. If the member 58 is distorted in the moving direction, the coating width cannot be varied with high accuracy. Therefore, it is important that the seal member 58 is not distorted in the moving direction.

  Here, that the seal member 58 is distorted in the moving direction means that the seal member 58 is distorted so that the seal member 58 is inclined as a result of the movement of the lower portion being delayed with respect to the movement of the upper portion of the seal member 58.

  Next, the sealing is performed so that the ball screw 64 for moving the sealing member 58 is not deformed as much as possible due to the surface pressure, and the sealing member 58 is not distorted by the frictional resistance due to the surface pressure when the sealing member 58 is moved away or approached. A second embodiment of the coating head 18 in which the structure of the member 58 and the moving structure are improved will be described.

[Second Embodiment of Coating Head]
FIG. 8 is an exploded view of the second embodiment of the coating head 18, and FIG. 9 is a cross-sectional view in the X-axis direction of the coating head 18 assembled from the exploded view of FIG.

  As shown in FIGS. 8 and 9, dovetail grooves 78 are formed in the Y-axis direction on the upper surface of the central portion at the lower portions of both ends in the application width direction (Y-axis direction) of the liquid reservoir portion 54 formed as a rectangular cavity portion. The pair of dovetail blocks 76 and 76 formed are fixed in close contact with the wall surface of the liquid reservoir 54. In the Y-axis direction of the dovetail groove 78, a narrow communication nozzle 80 that penetrates from the upper surface of the center portion of the dovetail groove 78 to the lower surface of the center portion and communicates with the linear nozzle 28 is formed.

  On the other hand, at the lower end portion of the moving block 68 to which the ball screw 64 is screwed, a dovetail groove engaging portion 82 is formed that is slidably engaged with the dovetail groove 78 of the dovetail block 76 (in the Y-axis direction). A slit hole 84 is formed in the center of the joint portion 82 in the Y-axis direction. A sealing member 58 that is slidably fitted to the linear nozzle 28 is inserted and fixed in the slit hole 84.

  As described above, the moving block 68 is slidably engaged with the dovetail groove 78 of the dovetail block 76 (in the Y-axis direction), so that the straightness of the moving block 68 moving in the Y-axis direction can be improved. Thereby, since the burden to the ball screw 64 resulting from the surface pressure of the sealing member 58 and the wall surface (seal surface 28B) of the linear nozzle 28 can be reduced, deformation of the ball screw 64 can be suppressed.

  FIG. 10 is a perspective view of a plate-like seal member 58 used in the second embodiment of the coating head 18.

  As shown in FIG. 10, the seal member 58 is formed by bonding a plurality of (three types in FIG. 10) thin metal plates having different lengths to a laminated structure. That is, both the upper half surfaces of the longest first plate 86 are sandwiched and bonded together by the next long pair of second plates 88 and 88, and the substantially upper half surfaces of the second plate are bonded together. It is formed in a five-layer structure sandwiched between three plates 90 and 90 and bonded together. As the material of the seal member 58, the above-described spring steel can be preferably used.

  Then, the base end portion 90A of the thickest five-layer structure portion of the seal member 58 is fitted and fixed in the slit hole 84 formed in the joint portion 82 of the moving block 68 described above. Further, an intermediate portion 88A of the second thickest three-layer structure portion of the seal member 58 and a tip portion 86A of the thinnest single-layer structure are fitted into the linear nozzle 28, and the upper end portion of the linear nozzle 28 is also inserted. Is widened so as to correspond to the thickness of the intermediate portion 88A of the seal member 58.

  Thus, by making the sealing member 58 the laminated structure of FIG. 10, the rigidity increases as the distance from the distal end portion 86A to the proximal end portion 90A increases, and the thin distal end portion 86A corresponding to the film thickness of the coating film increases. The length in the Z-axis direction can be shortened. Thereby, when the seal member 58 is moved, the seal member 58 can be made difficult to be distorted in the Y-axis direction by the frictional resistance due to the surface pressure.

  In the second embodiment of the coating head, an example in which a plurality of thin metal plates having different lengths are bonded to the laminated structure as the plate-like seal member 58 has been described. A bent structure can also be used.

  Moreover, since the sealing member 58 shown in the first and second embodiments of the coating head 18 is made of metal but is formed of a thin plate, there is a concern about wear and metal fatigue for long-term use. Therefore, it is necessary to sufficiently design the strength.

[Third Embodiment of Coating Head]
In the third embodiment of the coating head 18 shown in FIG. 11, the coating width variable mechanism 44 has a structure in which the seal member 58 is not used, so that the coating life variable mechanism 44 having a long life is configured. The same members as those in the first embodiment and the second embodiment will be described with the same reference numerals.

  As shown in FIG. 11, in the coating head 18 of the third embodiment, the liquid reservoir 54 is formed by bonding two metal thick plates 46A and 46B together as in the first and second embodiments. Instead of forming, a cylindrical hole penetrating in the Y-axis direction is formed in a rectangular solid body block 92, and both ends of the cylindrical hole are closed by a pair of side plates 94, 94. That is, the casing portion of the coating head 18 in which the liquid reservoir 54 is formed is formed as a rectangular parallelepiped pressure vessel structure.

  In addition, the material of the main body block 92 and the side plate 94 should just have the hardness which can be satisfied as a pressure vessel structure, and should be easy to process, for example, can use a metal and an acrylic resin suitably. Moreover, in FIG. 11, it has illustrated typically so that the inside of the liquid reservoir part 54 may be seen.

  A pair of columnar seal members 96, 96 are slidably fitted (in the Y-axis direction) inside the cylindrical hole-shaped liquid reservoir 54, and a cylindrical seal is formed at the center of the liquid reservoir 54 in the Y-axis direction. A ball screw 64 for moving the members 96 and 96 apart and close is provided.

  The cylindrical seal members 96 and 96 are moved by rotating the ball screw 64 by a servo motor 74 mounted outside the coating head 18. The servomotor 74 and the ball screw 64 are connected by a power transmission mechanism such as a gear 72 (only some gears are shown).

  Accordingly, when the ball screw 64 is rotated by driving the servo motor 74, the pair of columnar seal members 96, 96 move away from and approach each other while sliding on the inner wall surface of the cylindrical liquid reservoir portion 54. As a result, the cavity length in the Y-axis direction of the liquid reservoir 54 is varied, and accordingly, the inlet width of the inlet of the linear nozzle 28 (opposite the discharge port) is changed.

  Further, a narrow slit-like nozzle 98 penetrating from the liquid reservoir 54 to the lower surface of the main body block 92 is cut. A tip block 100 having an inverted triangular cross section (radial cross section) having a linear nozzle 28 communicating with the nozzle 98 is connected and fixed to the lower surface of the main body block 92.

  That is, in the coating head 18 of the third embodiment, the pair of columnar seal members 96, 96 move, and the inlet (opposite side of the discharge port) of the linear nozzle 28 is narrowed or expanded. The opening length (application width) of the linear nozzle 28 is variable. The material of the cylindrical seal member 96 is preferably formed of a relatively soft metal such as brass or a plastic having excellent wear resistance typified by PTFE (Teflon (registered trademark)).

  As can be seen from FIG. 11, in the third embodiment of the coating head 18, the sealing surface is the entire outer peripheral surface of the cylindrical seal members 96, 96, and a large surface pressure is required for sealing. do not do. Therefore, since a structure excellent in wear resistance and fatigue resistance in repeated use of the coating head 18 can be provided, the service life is long.

  As a modification of the third embodiment of the application head 18 that varies the application width of the linear nozzle 28 by narrowing or widening the inlet width of the linear nozzle 28, as shown in FIG. It is also conceivable to provide planar seal members 102, 102 on the lower surface of the seal member holding block 70 of the coating width varying mechanism 44 in FIG. 4 to narrow or widen the inlet of the linear nozzle 28.

  However, the two metal thick plates constituting the coating head 18, that is, the combined surfaces of the chamber plate 46 </ b> A and the blocking plate 46 </ b> B are unlikely to be the same surface, and a step is easily formed on the lower surface of the liquid reservoir 54. Further, the flat seal member 102 has a very large frictional force due to a load for generating a surface pressure, and has a large resistance in the direction opposite to the moving direction.

  Therefore, there is a concern that the moving speed may be adversely affected, or the posture is likely to change depending on the moving direction of the planar seal member 102, and the sealing performance is deteriorated.

[Method for forming circular coating on circular substrate]
Next, a method for actually forming a circular coating film having the same size as that of the circular substrate 12 on the surface of the circular substrate 12 using the coating apparatus 10 according to the embodiment of the present invention described above will be described. In the following description, the case of the coating head 18 described in the first embodiment will be described.

  In the coating apparatus 10 according to the embodiment of the present invention, the control unit 26 controls the coating width variable mechanism 44 and the X-axis moving mechanism 36 so that the pair of seal members 58 and 58 are linear nozzles during the coating process time. A circular coating film is formed on the circular substrate 12 by synchronizing the opening / closing speed for opening and closing the opening 28 and the moving speed at which the circular substrate 12 moves. Here, synchronization refers to associating the timing of the opening / closing speed and the moving speed.

  In other words, in the coating apparatus 10 according to the embodiment of the present invention, the control unit 26 controls the X-axis moving mechanism 36 of the substrate table 16 and the coating width variable mechanism 44 provided in the coating head 18 as instructed so as to be circular. While moving the substrate 12 in the X-axis direction at a predetermined movement speed, in synchronization with this movement, the opening of the linear nozzle 28 of the coating head 18 is opened and closed at a predetermined opening / closing speed, and the coating width is increased in the Y-axis direction. A circular coating film is realized on the circular substrate 12 by being variable.

  Accordingly, the coating apparatus 10 according to the embodiment of the present invention does not rotate the circular substrate 12 at all as in the spin coating method in order to form a circular coating film on the surface of the circular substrate 12.

  By the way, even if the coating apparatus 10 according to the embodiment of the present invention realizes a circular coating film shape, the film thickness uniformity, which is said to be the greatest advantage in the spin coating method, can ensure the same or better performance. is necessary.

  In the following description, important points for forming a flat circular coating film with good film thickness uniformity by the coating apparatus 10 of the present invention will be described.

  The first important point is to keep the coating gap, which is the gap between the surface of the circular substrate 12 and the discharge port 28A of the linear nozzle 28 of the coating head 18, parallel and constant in the coating width direction (hereinafter referred to as “ This is called “application gap adjustment”). For this reason, the Z-axis moving mechanism 24 described above requires an actuator for vertical movement that correctly stabilizes the coating head 18. For example, the application gap can be accurately set by the Z-axis moving mechanism 24 configured by a ball screw with a brake. This is a necessary condition for making the film thickness constant. Of course, after the coating, further planarization treatment may be performed by rotating as in the spin coating method, but this is not intended by the present invention.

  The second important point is that the discharge amount of the coating liquid from the coating head 18 is greatly different between forming a rectangular coating film and forming a circular coating film. That is, when forming a rectangular coating film, the discharge amount of the coating liquid from the coating head 18 may be made constant during the coating process time. On the other hand, when forming a circular coating film, it is necessary to change the opening length (application width) of the linear nozzle 28 during the application process time. To fluctuate.

  Therefore, in order to form a circular coating film having a uniform film thickness with high accuracy, the coating liquid discharged from the coating head 18 in accordance with the opening length (coating width) of the linear nozzle 28 during the coating process time. It is necessary to introduce an application control system that variably controls the discharge amount with high accuracy (hereinafter referred to as “variable control of the discharge amount”).

  However, in the coating control system, it is very difficult to measure the discharge amount from the coating head 18 in real time during the coating process time. Therefore, if a different physical quantity corresponding to the discharge amount is searched and a coating control system is constructed based on this, it is considered that the film thickness can be made constant even in coating where the discharge amount varies.

  Therefore, as a different physical quantity corresponding to the discharge amount, in the coating apparatus 10 according to the embodiment of the present invention, the pressure sensor 31 is provided in the coating head 18 as described above, and the internal pressure of the coating head 18 (the liquid reservoir 54) Fluid pressure).

  FIG. 13A shows the relationship between the discharge rate (mL / s) from the coating head 18 and the rotational speed (rps) of the supply pump 30. FIG. 13B shows the relationship between the internal pressure (kPa) of the coating head 18 and the rotational speed (rps) of the supply pump 30. FIG. 13C shows the relationship between the discharge amount (mL / s) from the coating head 18 and the internal pressure (kPa) of the coating head 18. Note that s in the unit represents seconds.

  The simplest preliminary test for obtaining the relationship between the discharge amount, the internal pressure, and the rotational speed in advance is the data obtained by increasing the rotational speed of the supply pump 30 in small steps and further decreasing in small steps. Is a way to take. At this time, while the circular substrate 12 is moved at a constant speed and coating is actually performed, fluctuations in the internal pressure of the coating head 18 corresponding to fluctuations in the rotation speed of the supply pump 30 are sequentially detected by the pressure sensor 31 described above. . In addition, the film thickness variation of the coating film corresponding to the rotation speed of the supply pump 30 and the opening length (coating width) of the linear nozzle 28 at that time are measured. Since the discharge amount is proportional to the product of the film thickness dimension and the application width dimension of the applied coating film at that time, it can be calculated.

  Then, the relationship between the discharge amount corresponding to the change in the rotation speed of the supply pump 30 changed stepwise, the internal pressure of the coating head 18, and the coating head 18 and the discharge amount is plotted. Thereby, the graph of the relationship shown to (A) of FIG. 13, (B), (C) can be obtained.

  Further, as more detailed data, the data of the internal pressure level of the coating head 18 at the start of discharge for discharging the coating liquid from the coating head 18 is clearly shown, and both the speed increasing process and the speed decreasing process of the supply pump 30 are performed. By measuring these characteristics, detailed data such as a response delay of a viscous fluid such as a coating liquid can be obtained.

  What I want to know most is the relationship between the internal pressure of the coating head 18 and the discharge amount from the coating head 18 shown in FIG. In this case, if the relationship between the discharge amount and the internal pressure is linear, the internal pressure corresponds to the opening length of the linear nozzle 28. In the case of non-linearity, it is necessary to approximate the relationship to a function and convert it into a considerable internal pressure. Thereby, the target internal pressure of the coating head 18 for each hour during the coating process time for forming the circular coating film on the circular substrate 12 is determined, and the ideal pressure pattern of the internal pressure from the start of coating to the end of coating is determined. . That is, in order to make the film thickness constant in the formation of the circular coating film, the required discharge amount is obtained from the opening length (application width) of the linear nozzle 28, and the internal pressure of the application head 18 corresponding to the value is ideal. A pressure pattern can be set. The set ideal pressure pattern is input in advance to the control unit 26 in order to shift to the rotation speed fluctuation command of the supply pump 30. And the control part 26 always monitors the internal pressure of the coating head 18 by the pressure sensor 31 during the coating process time. That is, the difference between the target internal pressure value for each time during the coating process time and the detected value of the pressure sensor 31 provided in the coating head 18 is grasped.

  And the control part 26 calculates the difference of the detected value of the pressure sensor 31 obtained by monitoring, and the setting value based on the set ideal pressure pattern, and feeds back to the rotational speed of the supply pump 30 so that a difference may be eliminated. Control. In other words, the difference between the target internal pressure value for each time during the coating process time and the detected value of the pressure sensor 31 provided in the coating head 18 is grasped, and feedback control is performed so as to fill the difference. That is, the control unit 26 controls to increase the rotation speed of the supply pump 30 when the detected value by the pressure sensor 31 is smaller than the set value of the ideal pressure pattern, and conversely, when the detected value is larger than the set value. First, the rotational speed of the supply pump 30 is controlled to be reduced. Thereby, it is possible to realize a good application with a circular application shape and a constant film thickness.

  As a method of the application control system in the control unit 26, the PID method is normally considered, but sufficient control is possible even with feedback of only the proportional portion (P). Nevertheless, there is a difference in behavior between when the discharge amount from the coating head 18 is increased with time and when it is decreased, and this is a major characteristic of viscous fluid. In this case, in the previous test, the problem can be solved by changing the control gain according to the test result of increasing or decreasing the rotational speed of the supply pump 30 stepwise or by introducing a response delay element for correction. This method can also handle orientation flats and notches.

  By introducing the coating control system for “coating gap adjustment” and “variable control of discharge amount” described above, it becomes possible to make the coating shape circular and the coating film thickness uniform and smooth. .

  (A) of FIG. 14 shows the opening / closing speed (mm / s) in the application width direction (Y-axis direction) of the pair of seal members 58, 58 during the application process time (s) for forming the circular coating film. (B) shows the moving speed (mm / s) of the circular substrate 12 in the moving direction (X-axis direction).

  Here, the opening / closing speed of the seal member 58 is a speed at which the pair of seal members 58, 58 are moved apart and moved in the application width direction by the seal member moving means 60 to open / close the opening of the linear nozzle 28. This is synonymous with the moving speed of the seal member 58.

  When forming a circular coating film on the circular substrate 12, as described above, in order to clarify the direction and position of the circular substrate 12, a notch K (refer to FIG. 15) called an orientation flat or notch is intentionally formed. Although it may be applied from any direction with respect to a position where the notch K is present, in the present embodiment, in order to facilitate understanding, application is started from a complete circular portion on the opposite side of the notch K, Consider a case where the application is completed at the notch K.

  That is, the application is started in a state where the opening of the linear nozzle 28 is completely closed by the pair of seal members 58, 58 (application width zero), and the opening (application width) is gradually widened to draw an upper semicircle, Thereafter, the opening (application width) was gradually closed, and application was terminated at the position where the notch K was formed.

  When the circular coating film is formed while moving the circular substrate 12 mounted on the substrate table 16 at a constant moving speed (X-axis speed) as shown in FIG. The opening / closing speeds (Y-axis speeds) 58 and 58 are as shown in FIG.

  FIG. 15 is a diagram in which a circular coating film having the same size as that of the circular substrate 12 is formed on the surface of the circular substrate 12 having the notch K, S indicates an application start point, and F indicates an application end point. Further, horizontal lines X1 to X10 are formed at equal intervals in the X-axis direction and indicate that the moving speed of the circular substrate 12 is constant. Y1 to Y10 are the lengths of the horizontal lines, and indicate the opening lengths (application widths) of the pair of seal members 58 and 58 corresponding to X1 to X10.

  As can be seen from FIG. 15, the application width increases rapidly from the application start point S to the vicinity of the application point X2, and then gradually increases from the application point X3 to the vicinity of X5, forming an upper semicircle. Thereafter, the coating width is gradually reduced from the coating point X6 to the vicinity of X9, and then sharply decreases from the coating point X9 to the coating end point F to form a lower semicircle having a notch K.

  This means that when the circular substrate 12 is moved at a constant moving speed (X-axis speed), the coating width of the linear nozzle 28 is sharply moved by moving the seal member 58 at a high opening / closing speed from the coating start point S. It means to make it bigger. Then, after slightly lowering the opening / closing speed of the sealing member 58 in the vicinity of the center of the circular substrate 12, the opening / closing speed is rapidly increased again from the vicinity of the end of application, and the application width of the linear nozzle 28 is rapidly reduced. We have to go. Thus, by synchronizing both the X-axis velocity and the Y-axis velocity with a predetermined velocity relationship, a circular coating film having the same size as the circular substrate 12 can be finally formed on the surface of the circular substrate 12. .

  As described above, the application width varying mechanism 44 for driving the pair of seal members 58 and 58 is all housed in the liquid reservoir 54 of the application head 18 except for the servo motor 74. The portion is filled with a high-pressure viscous fluid (coating liquid). For this reason, viscous frictional resistance is added to the entire coating width variable mechanism 44, and the smooth movement operation of the pair of seal members 58, 58 is hindered. For this reason, there is a possibility that the rapid response of the pair of seal members 58, 58 cannot obtain the expected response.

  Therefore, in order to achieve the formation of a circular coating film having a uniform film thickness, which is one of the initial purposes, the rapid deceleration and acceleration of the pair of seal members 58 and 58 are avoided, and the X-axis direction is avoided. It is more preferable to find a load condition that is not biased in any of the Y-axis directions.

  FIG. 16 shows the movement speed pattern of the circular substrate 12 so that rapid deceleration and acceleration of the pair of seal members 58 and 58 can be avoided as much as possible.

  FIG. 16A shows the opening / closing speed (mm / s) in the coating width direction (Y-axis direction) of the pair of seal members 58 and 58 during the coating process time (s) for forming the circular coating film. FIG. 16B shows a moving speed (mm / s) in the moving direction (X-axis direction) of the circular substrate 12 during the coating process time (s).

  As shown in FIG. 15, in the vicinity of the start of application and the vicinity of the end of application where the opening / closing speed of the pair of seal members 58, 58 needs to be increased or decreased rapidly, as shown in FIG. As described above, the moving speed of the circular substrate 12 is reduced. Then, in the coating central time zone in which the variation in coating width is small and the opening / closing speed of the pair of seal members 58 and 58 can be slowed, the moving speed of the circular substrate is increased as shown in FIG. That is, as shown in FIG. 16B, the moving speed pattern of the circular substrate 12 is changed to a sine wave pattern (FIG. 16 shows ½ of one cycle of the sine wave pattern). As a result, as shown in FIG. 16A, the opening / closing speed of the pair of seal members 58, 58 can be made a gentle sine wave pattern, so that the pair of seal members 58, 58 can be rapidly decelerated or increased. Speed can be avoided.

  Basically, it is an application of sine and cosine functions, and by setting a smooth speed fluctuation, the movement of the seal members 58 and 58 can be smoothly changed especially despite the interference of the viscous frictional resistance. That is, the opening / closing speed at the start and end of application of the pair of seal members 58, 58 is set to 0 (zero), and the opening / closing speed pattern during application is set to a sine wave pattern. On the other hand, smooth circular trajectory control can be performed by making the movement speed pattern of the circular substrate 12 a sine wave pattern delayed by a quarter period (phase difference 90 degrees) from the opening / closing speed pattern and performing circular application in synchronization. it can.

  FIG. 14 and FIG. 16 are clearly distinguished from each other by the difference in the fluctuation ratio of the opening and closing speeds of the seal members 58 and 58 during the coating process time. As can be seen from FIGS. 14 and 16, the change in the opening / closing speed of the seal member 58 is the same between the formation of the upper semicircle (10 seconds) and the formation of the lower semicircle (10 seconds) except that the sign is opposite. Shows shape variation. Therefore, the fluctuation ratio of the opening / closing speed of the seal member 58 with respect to the coating process time (20 seconds) (the difference between the maximum opening / closing speed and the minimum opening / closing speed) is 1/2 of the fluctuation ratio at the time of forming the upper semicircle or the lower semicircle. As calculated. 14 and 16, the coating process time of the circular substrate 12 per sheet is the same 20 seconds.

  Looking at the fluctuation ratio of the opening / closing speed of the seal member 58 according to this calculation, in the case of FIG. 14 where the moving speed of the circular substrate 12 is constant, the maximum speed and the minimum speed of the seal member 58 are 21: 0. The change ratio is 21).

  On the other hand, in the case of FIG. 16 in which the movement speed pattern of the circular substrate 12 is a parabolic shape, the maximum speed and the minimum speed of the seal member 58 are 7: 0 (when 0 is stationary), and the fluctuation ratio is 7. Therefore, as shown in FIG. 16, the seal member has a moving speed pattern of a circular substrate 12 which is a sine wave pattern delayed by ¼ period (phase difference 90 degrees) from the opening / closing speed pattern. It is clear that 58 can move very stably.

  FIG. 17 shows the change in the discharge amount (necessary discharge amount) corresponding to the opening length (application width) of the linear nozzle 28 during the application process time when the movement speed pattern of the circular substrate 12 is as shown in FIG. Is the result of A curve indicated by a dotted line in FIG. 17 is a discharge amount pattern, and a solid line is a movement speed pattern of the circular substrate 12.

  As shown in FIG. 17, when the movement speed pattern of the circular substrate 12 is as shown in FIG. 16, the discharge amount pattern is semicircular. That is, the discharge amount gradually increases from the start of application to the maximum, and thereafter gradually decreases until the end of application. This makes it possible to avoid a sudden increase or decrease in the opening / closing speed of the seal member 58 in the vicinity of the start of application and the vicinity of the end of application where the increase / decrease of the application width is large.

  As described above, by using the coating apparatus according to the embodiment of the present invention, by providing a control algorithm that synchronizes the moving speed (X-axis speed) of the circular substrate 12 and the opening / closing speed of the linear nozzle, A highly accurate circular coating film having a small distribution and the same circular shape as the circular substrate 12 can be realized.

  The coating apparatus 10 according to the embodiment of the present invention is a non-rotating type coating apparatus different from the spin coating method. Therefore, compared with a conventional coating apparatus for a circular substrate typified by a spin coating method, a new coating apparatus for a circular substrate that can shorten the tact time and can be applied to a high-viscosity material without secondary processing. Can be realized.

  Furthermore, because of the non-rotating type coating apparatus, the coating material used in the electronic device process, which is becoming expensive, can be reduced to about 1/20 to 1/10 of the conventional method. Can be expected.

  Finally, the effects of the coating apparatus 10 according to the embodiment of the present invention are summarized as follows.

  (A) Not only can a novel coating for forming a circular coating film on a circular substrate be realized, but also a high-precision coating with a small variation in film thickness can be achieved.

  (B) Since it is a slit coat method, it can apply | coat with the application quantity required for application | coating, and a useless coating liquid does not generate | occur | produce like a spin coat method.

  (C) Since the coating liquid is not scattered from the circular substrate unlike the spin coating method, problems due to the scattering of the coating liquid can be avoided, and secondary processing is not required.

  (D) Since the coating operation is handled in the same manner as a normal slit coating method, the tact time can be remarkably shortened compared to the spin coating method.

  (E) It has been clarified that it has many advantages such as a circular coating of a coating liquid of a high-viscosity material, which was not possible with the spin coating method.

  That is, the coating apparatus 10 according to the embodiment of the present invention maintains the advantage of forming a high-precision thin circular coating film that the spin coating method coating apparatus has, while maintaining the advantage of the spin coating method. All of “the efficiency problem”, “the secondary processing problem of removing the scattered coating liquid”, “the long production tact time”, and “the non-application of the high viscosity coating liquid” can be solved.

  Further, the effect of the coating apparatus 10 according to the embodiment of the present invention is that not only a circular coating film can be formed, but also coating films having various shapes can be formed.

  In the above-described embodiment, the circular coating film which is the best advantage of the present invention has been described. However, the coating apparatus 10 according to the embodiment of the present invention has a coating width provided in the coating head 18. There is a great merit that the application width can be changed by the variable mechanism 44.

  That is, in the conventional slit coating method coating head, as shown in FIG. 3, the coating width is uniquely determined by the opening length T of the predetermined spacer shim 3. For example, when application with a different application width is required, it is necessary to disassemble and wash the application head and replace it with another spacer shim 3 having a different application width, and perform the application operation again. This is a very inefficient process and takes time.

  In such a case, the coating apparatus 10 according to the embodiment of the present invention is at a position where the pair of seal members 58 and 58 of the coating width varying mechanism 44 provided in the coating head 18 are moved apart so as to have a predetermined coating width. By fixing, the coating width can be arbitrarily set, and the apparatus is easy to use. As a method for arbitrarily setting the coating width, the control unit 26 controls the servo motor 74 that rotates the ball screw 64 to move the separation distance between the pair of seal members 58 and 58 to a predetermined coating width. To stop. Alternatively, a mechanism capable of rotating the ball screw 64 with a manual rotating handle or the like can be separately incorporated.

  As a result, the coating head 18 according to the embodiment of the present invention can only cope with coating patterns of various shapes (for example, application of a large curvature portion or application of a notch portion in addition to a triangle, a trapezoid, and a polygon). In addition, it is possible to provide a coating head 18 with a variable coating width that does not require a change in spacer shim.

  DESCRIPTION OF SYMBOLS 1 ... Conventional coating head, 2A ... Chamber plate, 2B ... Blocking plate, 3 ... Spacer shim, 4 ... Liquid reservoir part, 5 ... Liquid feeding pipe, 10 ... Coating apparatus, 12 ... Circular substrate, 14 ... Casing, 14A ... Base Base room, 14B ... coating chamber, 16 ... substrate table, 18 ... coating head, 20 ... gantry structure, 22 ... Y-axis moving mechanism, 24 ... Z-axis moving mechanism, 26 ... control unit, 28 ... linear nozzle, 28A DESCRIPTION OF SYMBOLS ... Discharge port, 28B ... Sealing surface, 30 ... Supply pump, 31 ... Pressure sensor, 31A ... Sensor part, 32 ... Liquid feeding pipe, 33 ... Coating liquid tank, 34 ... Servo motor, 35 ... Through-hole, 36 ... X axis Moving mechanism, 36A ... Rail, 36B ... X-axis slider, 38 ... Rotating mechanism, 40 ... Vacuum pump, 42 ... Touch panel, 43 ... Lift pin mechanism, 44 ... Variable coating width mechanism, 46 ... Housing, 46A ... H Bar plate, 46B ... blocking plate, 48 ... spacer shim, 48A ... upper spacer shim, 48B ... lower spacer shim, 50 ... connecting hole, 52 ... cylindrical hole, 54 ... liquid reservoir, 56 ... air vent, 58 ... seal member, 58A ... Insertion portion, 58B ... fixing portion, 60 ... sealing member moving means, 62 ... sealing member housing portion, 64 ... ball screw, 66 ... bearing, 68 ... moving block, 69 ... shaft sealing member, 70 ... sealing member holding block, 72 ... Gear 74, Servo motor 76, Dovetail block 78, Dovetail groove 80, Communicating nozzle 82 82 Joint portion 84 Slit hole 86 First plate 88 88 Second plate 90 Third Plate, 92 ... Main body block, 94 ... Side plate, 96 ... Cylindrical seal member, 98 ... Nozzle, 100 ... Tip block, 102 ... Flat seal member

Claims (12)

The coating liquid is supplied from the linear nozzle, which includes a liquid reservoir that spreads the supplied coating liquid in the coating width direction and a linear nozzle that has a slit-like opening continuously formed in the liquid reservoir. In the slit coat method coating head that forms a coating film on the surface of the substrate to be coated by discharging,
An application head characterized in that an application width variable mechanism for changing an application width of an application liquid discharged from the linear nozzle is provided. The coating width variable mechanism is
A pair of plate-like seal members that are fitted in the slit-like openings of the linear nozzles so as to be movable in the application width direction, and seal the fitted openings;
The coating head according to claim 1, further comprising: a seal member moving unit that opens and closes the opening of the linear nozzle by moving the pair of seal members apart and approaching in the coating width direction.   The coating head according to claim 2, wherein the plate-shaped sealing member is formed in a bent structure in which a metal thin plate is bent in a V shape, and the V-shaped portion is fitted into the linear nozzle.   The plate-like seal member is formed by laminating a plurality of thin metal plates having different lengths in a laminated structure, a thick portion is supported by the seal member moving means, and a thin portion is the linear nozzle. The application head according to claim 2, which is inserted and inserted. The seal member moving means includes
A pair of moving blocks provided in the application width direction of the liquid reservoir,
A right screw and a left screw are formed at the center of the coating width direction, and a ball screw that penetrates the pair of moving blocks into the right screw and the left screw, respectively,
The coating head according to claim 2, further comprising: a servo motor that rotates the ball screw. The seal member moving means includes
The liquid reservoir portion is provided in close contact with the liquid reservoir portion at both ends of the application width direction in the application width direction, and a dovetail groove is bored in the application width direction on the upper surface of the central portion, and the center from the upper surface of the central portion inside the dovetail groove. A dovetail block in which a gap penetrating the lower surface of the portion and communicating with the linear nozzle is formed;
The coating head according to claim 5, further comprising a mating portion formed at a lower end portion of the pair of moving blocks and slidably mated with the dovetail groove. The coating width variable mechanism is
A pair of columnar seal members that are movably fitted in the application width direction of the liquid reservoir formed as a hollow portion having a cylindrical hole shape, and seal the fitted cavity;
A seal member moving means for moving the pair of columnar seal members apart and approaching in the application width direction; and
The coating head according to claim 1, wherein the coating width is varied by opening and closing an opening inlet of the linear nozzle continuous with the liquid reservoir by movement of the pair of cylindrical seal members. While supplying the coating liquid to the liquid reservoir of the coating head by a constant flow rate supply pump, while discharging the coating liquid from the linear nozzle having a slit-like opening continuously formed in the liquid reservoir, A slit for forming a coating film on the surface of the substrate to be coated by relatively moving at least one of the coating head and the substrate to be coated in a direction orthogonal to the coating width direction of the linear nozzle. In the coating method coating apparatus,
An application head comprising the application width variable mechanism according to any one of claims 1 to 7,
An X-axis movement mechanism for relatively moving at least one of the coating head and the substrate to be coated;
A Z-axis moving mechanism for adjusting a gap between the discharge port of the linear nozzle of the coating head and the surface of the substrate to be coated;
A coating apparatus comprising: a coating width variable mechanism, an X-axis movement mechanism, and a control unit that controls at least the Z-axis movement mechanism.   The control unit controls the coating width variable mechanism and the X-axis moving mechanism, and during the coating process time, a pair of seal members open and close the opening / closing speed of the linear nozzle and the substrate to be coated moves. The coating apparatus of Claim 8 which forms a circular coating film in the said to-be-coated substrate by synchronizing with the moving speed to perform.   The control unit sets the open / close speed at the start and end of application of the pair of seal members to 0 (zero) and the open / close speed pattern of the open / close speed during the application process time as a sine wave pattern, 10. The coating according to claim 9, wherein the circular coating film is formed by using a movement speed pattern of the movement speed of the substrate to be coated as a sine wave pattern delayed by a 1/4 cycle (phase difference of 90 degrees) from the opening / closing speed pattern. apparatus. The application head is provided with a pressure sensor for detecting an internal pressure of the application head, and the application process time from the start of application to the end of application obtained by a preliminary test for forming a circular coating film on the substrate to be applied is described above. The relationship between the ideal pressure pattern of the internal pressure of the coating head according to the opening / closing operation of the linear nozzle and the discharge amount pattern from the coating head is input to the control unit,
The controller controls the rotation speed of the supply pump so that the difference between the detected value of the pressure sensor and the set value of the ideal pressure pattern becomes zero during the coating process time, and the coating liquid from the coating head The coating apparatus of Claim 9 or 10 which varies the discharge amount of.   The control unit controls the coating width variable mechanism before starting the coating and sets the predetermined coating width to stop the control of the coating width varying mechanism and start coating to apply a rectangular coating on the surface of the substrate to be coated. The coating apparatus of Claim 8 which forms a film | membrane.