JP2018118197A - Coating liquid coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating liquid coating method capable of forming a thin film having excellent in-plane uniformity, even in the case of a spray type.SOLUTION: A control part sprays coating liquid onto the whole surface of the substrate with a spray nozzle, while heating a substrate by a heater (t1-t2). Then, the coating liquid is spread over the whole surface of an irregular part on the substrate, to thereby form a uniform coating film on the substrate. Thereafter, the control part rotates the substrate and evaporates a solvent in the coating film (t3-t6), and therefore can form a thin film having excellent in-plane uniformity, even in the case of a spray type.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a semiconductor wafer, a liquid crystal display substrate, a plasma display substrate, an organic EL substrate, an FED (Field Emission Display) substrate, an optical display substrate, a magnetic disk substrate, a magneto-optical disk substrate, and a photomask substrate. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid coating method for forming a coating film by supplying a coating liquid to a substrate or a solar cell substrate (hereinafter simply referred to as a substrate), and in particular, for forming a coating film by a spraying technique. Regarding technology.

  When a coating liquid such as a photoresist liquid is applied to a substrate or the like to form a coating film, the coating is generally performed by a spin coating method. In this spin coating, a uniform coating can be applied uniformly from the thin film to the thick film in the thickness of the coating film. However, in MEMS (Micro Electro Mechanical Systems) or the like, a step in a pattern on a substrate is, for example, 100 to 200 μm, and the uneven portion is very large. Therefore, there is a problem that it is difficult to uniformly apply the coating liquid to the pattern bottom and side walls.

  Therefore, in order to solve such problems, the following spray-type application methods have been proposed.

  As a first method, a support base that supports the substrate, a rotating unit that rotates the support base, a heater that is provided in the support base and heats the substrate supported by the support base, and a substrate surface on the support base In some cases, the coating is performed by a substrate processing apparatus including a nozzle for spraying a coating liquid and a swinging unit that swings the nozzle in the horizontal direction above the substrate (see, for example, Patent Document 1).

  In this first method, while the substrate is heated by a heater and the substrate is rotated at a low speed in a horizontal plane, the nozzle is moved above the substrate and the coating liquid is sprayed from the nozzle to spray the entire surface of the substrate. Apply the coating solution to As a result, the solvent is volatilized by heat from the coating liquid sprayed and covers the entire surface of the substrate thickly, so that the fluidity of the coating film is reduced and the coating liquid is evenly applied even to a substrate having large uneven portions. be able to.

  In addition, as a second method, the first step of applying the coating liquid to the substrate by spin coating or spray coating, forming a film up to an intermediate depth position of the uneven portion, and reflowing the coating liquid by heating, and spray coating There is a method comprising a second step of heating the coating liquid later to form a coating film on the upper surface of the convex portion (see, for example, Patent Document 2).

  In this second method, the application is performed twice in the first step and the second step, and heating is performed during the second application, so that the flow of the coating solution can be suppressed. Therefore, the coating film can be formed as a uniform thick film.

Japanese Patent No. 3958717 Japanese Patent No. 5231072

However, the conventional example having such a configuration has the following problems.
That is, while the conventional first method and second method can form a thick coating film uniformly, it is difficult to uniformly form a thin coating film (for example, 1 μm or less). There is a problem that.

  In addition, the inventors conducted an experiment in the first conventional method described above by replacing the coating liquid with a low-viscosity one. However, in the thin film, the droplet of the coating liquid sprayed from the nozzle has a direct influence. However, only a thin film lacking in-plane uniformity could be formed. In addition, we changed the nozzle to be able to spray the coating liquid with smaller droplets, or applied ultrasonic waves to make the droplets of the coating liquid sprayed from the nozzle smaller. However, a good thin film could not be obtained.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a coating liquid coating method capable of forming a thin film with good in-plane uniformity even in a spray type. .

In order to achieve such an object, the present invention has the following configuration.
That is, the invention described in claim 1 is a coating liquid coating method for supplying a coating liquid to a substrate having a concavo-convex portion on a surface, a spraying process of spraying the coating liquid on the entire surface of the substrate, and rotating the substrate. And a rotating process of evaporating the solvent of the coating film in that order.

  [Operation / Effect] According to the first aspect of the present invention, when the coating liquid is sprayed on the entire surface of the substrate in the spraying process, the coating liquid is spread over the entire surface of the concavo-convex portion to form a uniform coating film. Thereafter, the substrate is rotated during the rotation process to evaporate the solvent of the coating film of the coating film, thereby forming a good thin film.

  In the present invention, it is preferable that the substrate is heated at a predetermined heating temperature in the spraying process.

  Since the fluidity of the sprayed coating liquid is reduced to some extent by heating at the heating temperature, the coating film coating liquid due to the centrifugal force in the rotation process is prevented from flowing more than necessary, and the in-plane uniformity can be improved.

  In the present invention, the predetermined heating temperature is preferably in a range from a temperature higher than room temperature to a temperature that gently lowers the fluidity of the coating solution supplied to the substrate.

  When the heating temperature is room temperature or lower, the fluidity of the sprayed coating solution is too high, and excessive flow occurs due to centrifugal force, so that the thickness of the coating cannot be made uniform. On the other hand, if the temperature is higher than the temperature at which the fluidity of the coating liquid supplied to the substrate is gradually lowered, the fluidity will rapidly decrease in a short time, and the coating liquid cannot be flowed by centrifugal force. The film thickness cannot be made uniform.

  Moreover, in this invention, it is preferable that the said predetermined heating temperature is the range of 30-50 degreeC (Claim 4).

  When the predetermined heating temperature is set to 30 to 50 ° C., the fluidity of the sprayed coating liquid can be appropriate for making the film thickness uniform by centrifugal force.

  In the present invention, it is preferable that in the spraying process, the rotation support portion supporting the substrate is heated with a heater.

  Since it heats from the lower surface of a board | substrate, heat can be efficiently transmitted to a coating liquid and the solvent contained in a coating liquid can be volatilized efficiently.

  In the present invention, it is preferable that in the spraying process, the substrate is heated with a lamp.

  Since wiring or the like is not necessary in the rotating portion, the structure of the rotation support portion can be simplified. Accordingly, it is possible to reduce the cost of an apparatus that performs this coating method.

  In the present invention, it is preferable that the spraying process and the rotating process are performed in the same apparatus.

  Since the rotation process can be carried out in a short time after the spraying process, the coating film can be formed efficiently.

  In the present invention, it is preferable that the spraying process and the rotating process are performed by separate devices.

  A thin film having a uniform thickness can be formed by performing only the spraying process in one apparatus and then performing the rotation process in another apparatus. Therefore, an improvement in throughput can be expected by carrying out with an apparatus specialized for spraying and heating and an apparatus specialized for rotation.

  According to the coating liquid coating method of the present invention, when the coating liquid is sprayed on the entire surface of the substrate in the spraying process, the coating liquid is spread over the entire surface of the concavo-convex portion to form a uniform coating film. Thereafter, the substrate is rotated during the rotation process to evaporate the solvent of the coating film of the coating film, thereby forming a good thin film.

1 is a plan view showing a schematic configuration of a substrate coating apparatus according to Example 1. FIG. 1 is a side view illustrating a schematic configuration of a substrate coating apparatus according to Embodiment 1. FIG. It is a time chart which shows an example of processing. It is a schematic diagram which shows a spraying process. It is a schematic diagram which shows a rotation process. It is a side view which shows schematic structure of the board | substrate coating device which concerns on Example 2. FIG. It is a figure where it uses for description of the board | substrate coating device which concerns on Example 3. FIG. It is a graph which shows an example of the relationship between mounting base temperature and the amount of solvent evaporation.

  Hereinafter, various methods for performing a coating process on a substrate will be described with reference to the drawings.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view illustrating a schematic configuration of the substrate coating apparatus according to the first embodiment, and FIG. 2 is a side view illustrating a schematic configuration of the substrate coating apparatus according to the first embodiment.

  The substrate coating apparatus 1 applies a coating solution to the substrate W to form a film. The substrate W in the present embodiment is, for example, a circular wafer in plan view. Moreover, the coating liquid in a present Example is a photoresist liquid used by photolithography, for example.

  The substrate coating apparatus 1 includes a rotation support unit 3, a delivery mechanism 5, a spray unit 7, and a cover unit 9.

  The rotation support unit 3 includes an electric motor 11, a rotation shaft 13, and a mounting table 15. The electric motor 11 is connected to one end side of the rotary shaft 13 so as to be rotatable around the vertical axis P. The electric motor 11 rotates counterclockwise in plan view. The other end side of the rotating shaft 13 is connected to the lower surface of the mounting table 15. The rotary shaft 13 is formed hollow inside and penetrates the electric motor 11 up and down. The upper part of the rotating shaft 13 is connected to a suction port (not shown) of the mounting table 15, and the hollow part of the rotating shaft 13 is connected to a vacuum line of a utility (not shown) at the bottom. The mounting table 15 has through-holes 17 at positions corresponding to the vertices of the regular triangle in plan view. The mounting table 15 has a diameter slightly smaller than the diameter of the substrate W, and a heater 19 is embedded therein. The heater 19 heats the substrate W placed on the placement table 15 from the lower surface.

  A delivery mechanism 5 is disposed below the mounting table 15. The delivery mechanism 5 includes an elevating member 21, three delivery pins 23 (only two are depicted in FIG. 2 because of the relationship in the illustrated direction), and an elevating drive unit 25. The elevating member 21 has an annular shape in plan view and is inserted through the rotation shaft 13. In the elevating member 21, each delivery pin 23 is erected at a position corresponding to each through hole 17. The raising / lowering member 21 is partially connected to the operating piece of the raising / lowering drive unit 25. The raising / lowering drive part 25 is comprised with the air cylinder, for example. When the lifting drive unit 25 is not in operation, the delivery pin 23 is positioned at the height position (withdrawal position) of the solid line in FIG. 2, and when the lifting drive unit 25 is in operation, the height of the two-dot chain line in FIG. The delivery pin 23 is located at the position (delivery position). The withdrawal position is a height position when the substrate W is processed, and the delivery position is a height position when the substrate W is delivered to and from a transport mechanism (not shown).

The spray unit 7 includes a spray nozzle 27, a support unit 29, and a horizontal drive unit 31. The spray nozzle 27 is supplied with a process gas and a coating liquid, and sprays the coating liquid toward the surface of the substrate W in a mist form. Examples of the process gas include nitrogen gas (N ₂ gas). Examples of the coating liquid include those having a viscosity of 10 cp. The spray nozzle 27 is attached to the distal end side of the support portion 29. A base end portion of the support portion 29 is connected to the horizontal drive portion 31. The horizontal drive unit 31 includes a screw shaft 33, an electric motor 35, a guide shaft 37, and a moving member 39. The screw shaft 33 is disposed horizontally with its axis directed in the diameter direction of the substrate W. One end side of the screw shaft 33 is connected to the rotation shaft of the electric motor 35. On the side of the mounting table 15 adjacent to the screw shaft 33, a guide shaft 37 is arranged in parallel to the screw shaft 33. The moving member 39 is screwed into the screw shaft 33 and is inserted through the guide shaft 37. Accordingly, when the electric motor 35 is driven, the moving member 39 moves along the screw shaft 33 and the guide shaft 37, and the opposite side of the standby position indicated by the solid line in FIG. The spray nozzle 27 moves between the two-dot chain line). The spray nozzle 27 is set such that the spray range of the coating liquid is at least equal to or larger than the diameter of the substrate W in the direction orthogonal to the moving direction of the spray nozzle 27. In addition, at least the diameter of the substrate W may be set in the moving direction of the spray nozzle 27.

  A cover portion 9 is disposed around the rotation support portion 3. The cover unit 9 prevents scattering of the coating liquid sprayed from the spray nozzle 27, prevents scattering of the coating liquid that scatters around from the substrate W, and collects the scattered coating liquid together with an airflow from above. To do. Specifically, the cover portion 9 includes an inner wall portion 41 and an outer wall portion 43. The inner wall portion 41 has an inclined surface from the side surface of the mounting table 15 toward the obliquely outer lower side, and the lower portion is in a vertical posture. The outer wall portion 43 is erected away from the inner wall portion 41 and has an opening at a position away from the mounting table 15. The lower part of the space surrounded by the inner wall part 41 and the outer wall part 43 is used for draining the coating liquid and discharging the gas containing the coating liquid mist and solvent.

  The above-described rotation control of the electric motor 11, temperature control of the heater 19, elevation control of the elevation drive unit 25, spray control by the spray nozzle 27, movement control of the spray nozzle 27 by the horizontal drive unit 31, mounting of the substrate W by the vacuum line. The suction / release control to the mounting table 15 is performed by the control unit 45 in an integrated manner.

  The control unit 45 includes a CPU and a memory (not shown), and controls each of the above-described units based on a recipe that is stored in advance in the memory and indicates how to apply.

  Here, a specific coating liquid coating method will be described with reference to FIGS. FIG. 3 is a time chart showing an example of processing. FIG. 4 is a schematic diagram showing a spraying process, and FIG. 5 is a schematic diagram showing a rotation process.

  In the initial state, the spray nozzle 27 is located at the standby position, the delivery pin 23 is at the withdrawal position, and the mounting table 15 is at a temperature of, for example, 40 ° C. due to the temperature control of the heater 19. First, the control part 45 operates the raising / lowering drive part 25, makes the delivery pin 23 protrude from the mounting base 15, and receives the board | substrate W in which the uneven | corrugated pattern was formed in the surface from the conveyance mechanism which is not shown in figure. Next, the control unit 45 deactivates the elevating drive unit 25 to retract the delivery pin 23 and activates vacuum suction to cause the substrate W to be vacuum-sucked on the mounting table 15.

  The control unit 45 operates the electric motor 35 of the horizontal drive unit 31 to move the spray nozzle 27 from the standby position into the outer wall unit 43. Then, the controller 45 allows the coating liquid to be sprayed from the spray nozzle 27 at the time point t1 and passes above the substrate W to the opposite side of the standby position across the substrate W (time point t2).

  The time points t1 to t2 described above correspond to the “spraying process” in the present invention.

  Thereafter, the control unit 45 operates the electric motor 35 to return the spray nozzle 27 to the standby position by time t3.

  Thereby, as shown in FIG. 4, the whole surface of the board | substrate W which has an uneven | corrugated | grooved part is covered with the coating film RF0. The coating film RF0 is in a state of 2 μm thicker than the target film thickness of 1 μm. In addition, the coating film RF0 is in a state where the film thickness in the surface of the substrate W is not uniform due to the influence of unevenness of spraying by the spray nozzle 27 and the like.

  The control unit 45 starts operating the electric motor 11 at time t3 and performs control so as to reach the rotational speed R1 at time t4. The rotation speed R1 is, for example, 1000 rpm. The electric motor 11 is controlled so that the rotational speed R1 is maintained until the time point t5 and then stopped at the time point t6. The interval between time points t4 and t5 varies depending on the viscosity of the coating film RF0 and the rotational speed R1, but is, for example, 30 seconds. After heating in this manner, by applying rotation, the coating solution of the coating film RF0 formed on the substrate W is appropriately flowed, so that the target film thickness is 1 μm and the in-plane uniformity is good. The coating film RF1 has a sufficient thickness.

  The above operation is from the time point t3 to the time point t6, and corresponds to the “rotation process” in the present invention.

  Thereafter, the control unit 45 operates the elevation driving unit 25 to raise the delivery pin 27 to the delivery position, and delivers the processed substrate W to a transport mechanism (not shown).

  According to the present embodiment, when the coating liquid is sprayed over the entire surface of the substrate W during the spraying process, the coating liquid is spread over the entire surface of the concavo-convex portion to form a uniform coating film RF0. Thereafter, by rotating the substrate W in the rotating process to evaporate the solvent of the coating film of the coating film RF0, the in-plane uniformity of the thickness of the coating film RF1 can be satisfactorily formed even in the spray type.

  Further, in this embodiment, the substrate W is heated by the heater 19, but since the substrate W is heated from the lower surface, the heat can be efficiently transmitted to the coating liquid, and the contained solvent can be efficiently removed. Can be volatilized. In addition, in this embodiment, since the spraying process and the rotation process are performed in the same apparatus, the coating film can be formed efficiently.

  Next, Embodiment 2 of the present invention will be described with reference to the drawings.

  FIG. 6 is a side view illustrating a schematic configuration of the substrate coating apparatus according to the second embodiment. In addition, about the same structure as Example 1 mentioned above, detailed description is abbreviate | omitted by attaching | subjecting a same sign.

  The substrate coating apparatus 1A does not include the heater 19 in the mounting table 15A. Therefore, a heating lamp 51 is provided on the inner surface of the outer wall 43. The lamp 51 irradiates light over the entire surface of the substrate W to heat the coating film RF0. The heating temperature is the same as in Example 1 described above.

  The present Example 2 has the same effect except that the heating method in the spraying process in Example 1 described above is different. Furthermore, since no wiring or the like is required in the rotating portion, the structure of the rotating mechanism can be simplified. Accordingly, it is possible to reduce the cost of an apparatus that performs this coating method.

  Next, Embodiment 3 of the present invention will be described with reference to the drawings.

  FIG. 7 is a diagram for explaining the substrate coating apparatus according to the third embodiment. In addition, about the same structure as Example 1 mentioned above, detailed description is abbreviate | omitted by attaching | subjecting a same sign.

  In Example 3, the substrate coating apparatus is composed of a plurality of apparatuses. Specifically, the spraying device 61, the transport device 71, and the rotation device 81 constitute the substrate coating device 1B.

  The spraying device 61 sprays the coating liquid from the spray nozzle 27 onto the substrate W. A heater 19 is embedded in the path along which the substrate W is transported. The substrate W to be transported is preferably heated by the heater 19 to 40 ° C., for example. The transport device 71 transports the substrate W on which the coating film has been formed by the spray device 61 to the rotating device 81. In addition, it may replace with this conveying apparatus 71, and you may make it an operator convey. The rotating device 81 rotates the substrate W sprayed with the coating liquid. In addition, the time interval (from time t2 to t3 in FIG. 3) after spraying the coating film to processing with the rotating device 81 is the viscosity of the coating film deposited on the substrate W, the degree of volatilization of the solvent, and the surrounding environment. Depending on the temperature and humidity, for example, it is about 5 to 10 minutes.

  In the third embodiment, only the spraying process is performed by the spraying device 61, and then the rotating process is performed by the rotating device 81. As in the first and second embodiments, the thin film having excellent in-plane thickness uniformity is used. The coating film can be formed. Therefore, an improvement in throughput can be expected by performing the processing with the spraying device 61 specialized for spraying and heating and the rotating device 81 specialized for rotation.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In the above-described first embodiment, the substrate W is fixed to the mounting table 15 by vacuum suction. However, even in an apparatus using a so-called mechanical chuck that locks the edge of the substrate with a holding pin or the like. Inventive methods can be implemented.

  (2) In each of the first to third embodiments described above, the substrate W is heated in the process of spraying the substrate W, but it may not be heated depending on the viscosity of the coating liquid and the temperature and humidity of the surrounding environment.

  (3) In each of Examples 1 to 3 described above, the heating temperature is set to 40 ° C., but the heating is not limited to this temperature in the present invention.

  The heating temperature in the spraying process is to make the viscosity suitable for obtaining fluidity that improves the uniformity of the film thickness. For example, the heating temperature may be in a range from a temperature higher than room temperature to a temperature that gently reduces the fluidity of the coating liquid supplied to the substrate W.

  This is because when the heating temperature is room temperature or less, the sprayed coating liquid has high fluidity and fluidity occurs, and thus the thickness of the coating cannot be made uniform. On the other hand, when the temperature is higher than the temperature at which the fluidity of the coating liquid supplied to the substrate W is gradually lowered, the solvent of the coating film is almost evaporated, and the solvent cannot be evaporated in the subsequent rotation process, so that a thin film cannot be formed. Because.

  As a specific range of the heating temperature, for example, 30 to 50 ° C. may be mentioned. However, since a suitable temperature differs depending on the temperature and humidity of the viscosity of the coating liquid, the characteristics of the solvent contained in the coating liquid, and the surrounding environment, it is preferable to conduct experiments in advance to obtain a suitable heating temperature.

  Reference is now made to FIG. FIG. 8 is a graph showing an example of the relationship between the mounting table temperature and the solvent evaporation amount. This graph shows the result of measuring the weight difference between the substrate W (200 mm diameter) on which the coating film RF0 is formed before and after heating at a heating temperature for a predetermined time.

  The above-described preferable heating temperature range of 30 to 50 ° C. indicates that the solvent of the coating film RF0 of the substrate W evaporates in the range of 0.05 to 0.1 [g]. Therefore, although the heating temperature varies depending on the viscosity of the coating film RF0, the degree of volatilization of the solvent, and the temperature and humidity of the surrounding environment, the weight of the solvent evaporated by heating the substrate W by the heater 19 may be in the above range.

DESCRIPTION OF SYMBOLS 1, 1A, 1B ... Substrate coating device W ... Substrate 3 ... Rotation support part 5 ... Delivery mechanism 7 ... Spraying part 9 ... Cover part 15 ... Mounting table 19 ... Heater 23 ... Delivery pin 25 ... Elevating drive part 27 ... Spray nozzle 35 ... Electric motor 41 ... Inner wall part 43 ... Outer wall part 45 ... Control part RF0, RF1 ... Coating film 51 ... Lamp 61 ... Spraying device 71 ... Conveying device 81 ... Rotating device

Claims (8)

In a coating liquid coating method for supplying a coating liquid to a substrate having an uneven portion on the surface,
A spraying process in which the coating liquid is sprayed on the entire surface of the substrate;
A rotating process of rotating the substrate to evaporate the solvent of the coating film;
Are applied in that order. In the coating liquid coating method according to claim 1,
In the spraying process, the substrate is heated at a predetermined heating temperature. In the coating liquid coating method according to claim 2,
The coating liquid coating method, wherein the predetermined heating temperature is in a range from a temperature higher than room temperature to a temperature that gently lowers the fluidity of the coating liquid supplied to the substrate. In the coating liquid coating method according to claim 3,
The said predetermined heating temperature is the range of 30-50 degreeC, The coating liquid coating method characterized by the above-mentioned. In the coating liquid coating method according to any one of claims 2 to 4,
In the spraying process, the rotating support part supporting the substrate is heated with a heater. In the coating liquid coating method according to any one of claims 2 to 4,
In the spraying process, the substrate is heated with a lamp. In the coating liquid coating method according to any one of claims 1 to 6,
The spraying process and the rotating process are performed by the same apparatus. In the coating liquid coating method according to any one of claims 1 to 6,
The spraying process and the rotating process are performed by a separate apparatus.

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