JP2005111411A - Coating film forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating film forming method in which chips are efficiently cut from a wafer, or the like by forming a flat coating film on which edge beads are decreased, and working steps are shortened and working cost is reduced because the removal of the edge beads is not required. <P>SOLUTION: In the coating film forming method for spreading and fixing a coating liquid on a substrate to form the coating film, a sheet-like material is brought into contact with the coating surface during or after spreading the coating liquid to remove at least a part of the coating liquid on the substrate to eliminate the flowability. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for forming a coating film having necessary flatness or unevenness on a substrate, for example, in components such as an image display device and an inkjet recording device, a printed circuit board, and other device components.

  Conventionally, in the manufacturing process of circuit boards, liquid crystal display elements, image forming apparatuses, ink jet recording apparatuses, etc., the substrate is coated with various materials such as metals, inorganic substances such as glass, organic substances such as resins, or mixtures thereof. A film is formed. In addition, various functions are expressed by stacking several coating films to form a device having a multilayer structure. Therefore, in many processes such as formation of these coating films, lamination of coating films, or patterning of coating films, a step of applying a coating solution is required.

  For example, in the manufacture of a semiconductor device such as a printed circuit board or IC, after forming a photoresist film on the substrate, the photoresist film is exposed and developed to form a predetermined pattern, and the patterned photoresist film is used as a mask. A method of processing the functional film into a predetermined pattern is used. In order to form this photoresist film, generally, a technique such as spin coating is used. For example, the photoresist film is manufactured by coating with a coating apparatus and a coating film forming method as disclosed in Patent Document 1 and the like.

  Further, with respect to a planarizing film such as a protective film for protecting against an etchant and chemicals / solvents and a passivation film, a method of applying a coating liquid such as a resist by a spin coating method and curing it is common. The spin coating method is used not only for flat surfaces but also for film formation on uneven surfaces. Patent Document 2 discloses such a coating apparatus and a coating film forming method.

  In manufacturing a liquid jet recording head device, for example, as shown in Patent Document 3, it is known to form several functional films using a spin coat method or the like.

  FIG. 10 shows a method for forming a coating film by spin coating. FIG. 10A is a schematic diagram showing an outline of the spin coating method, and FIG. 10B is a schematic diagram of a coating film formed by the spin coating method. In the figure, 1 is a substrate, 2 is a coating solution, and 3 is a coating film. 20 is a substrate support for the spin coater, and 23 is a coating liquid supply dispenser.

  First, the substrate 1 is brought into close contact with the substrate support 20 and chucked. The coating liquid 2 is appropriately supplied onto the substrate 1 from the coating liquid supply dispenser 23. Further, the substrate support 20 is rotated at a predetermined number of rotations as shown in the drawing to spread the coating liquid 2 on the substrate 1, and then dried on a hot plate (not shown), and FIG. A coating film 3 as shown in b) is obtained.

  As a method for forming a coating film, in addition to the spin coating method, as shown in Patent Document 4, a coating liquid is applied to a substrate from a slit-shaped coating head, and the coating head and the substrate are relative to each other in a direction perpendicular to the slit. There is also known a slit coating method in which a specific area on a substrate can be directly coated by moving it.

  Compared to the spin coating method in which the coating solution is shaken around to form a film, the coating solution can be applied only at a necessary place, and it is said that the usage efficiency of the coating solution is good.

JP-A-3-278854 Japanese Utility Model Publication No. 6-33150 JP-A-5-330066 JP 2000-5682 A

  However, in the spin coat method and the slit coat method shown in the prior art, as shown in FIG. 10B, an abnormally raised portion (edge bead) 4 occurs at the edge portion of the coating film, There was a problem that a hollow portion 5 having a slightly thin film thickness was generated inside. When the edge bead 4 and the recessed portion 5 are generated, the area of the flat portion 6 having a stable film thickness is significantly smaller than the area of the entire coating film 3. Therefore, when a large number of chips of a plurality of liquid jet recording head devices are taken from one substrate, the number of obtained chips is limited, and the size of the coating film and the substrate cannot be effectively utilized. Further, as a result, the use efficiency of the coating material is lowered, and the cost is increased.

  In the case of the slit coating method, it is considered that the edge bead 4 and the dent portion 5 are generated in the edge portion of the coating film in advance, and that the coating area is widened with respect to the flat portion 6 that requires a uniform film thickness. It has been. Thereby, a uniform film thickness can be ensured at least in a region where a uniform film thickness is required. However, the device becomes larger than necessary, and restrictions on device design occur when wiring or the like performed in a later process is performed, which is not realistic.

  Further, when it is desired to pattern the coating film 3 by photolithography or the like, the edge bead 4 may interfere with the mask alignment. For this reason, as disclosed in Patent Document 1, it is considered to remove the edge beads 4 by air or the like.

  However, the method of removing the edge bead 4 cannot increase the area of the flat portion 6, and the number of devices cut out is still affected by the edge bead 4 and the recessed portion 5. Further, when the edge bead 4 is removed, when a solvent or the like is used, a new bulge can be generated at the edge of the coating film due to the penetration of the liquid, or the structure of the coating film may be affected. It may occur.

  The shapes of the edge bead 4 and the recessed portion 5 are usually formed at a position about several mm to 10 mm from the edge portion of the coating film. However, since it is affected by properties such as the viscosity and drying property of the coating liquid 2, the thickness of the coating film 3, the method of fixing the coating liquid film applied by drying, etc., the conditions of the coating film depend on those conditions. It may extend to an area of 10 mm or more from the edge portion. Reduction of the edge beads 4 and the depressions 5 generated around the coating film is necessary for low-cost production of precision devices.

  The present invention has been made in view of the above circumstances, and the intended process is to reduce the edge beads and form a flatter coating film so that chips can be efficiently cut out from a wafer or the like, and the edge beads are removed. An object of the present invention is to provide a method for forming a coating film that can shorten the work process and reduce the work cost because it is not necessary.

  In order to achieve the above object, the present invention provides a coating film forming method in which a coating solution is stretched and fixed on a substrate to form a coating film, and a sheet-like object is brought into contact with the coating surface during or after the coating solution is stretched. The fluidity is lost by removing at least a part of the coating solution.

  According to the present invention, by extending the coating liquid onto the substrate or after extending, the sheet-like object is brought into contact with the coating surface, and at least a part of the solvent component is removed from the coating liquid to lose its fluidity. The edge bead can be reduced and a flatter coating film can be formed. Thereby, a chip can be efficiently cut out from a wafer or the like. Further, it is not necessary to remove the edge bead, the work process can be shortened, and the work cost can be reduced.

  In addition, according to the present invention, the drying accelerator is in contact with the surface of the coating liquid film during drying, so that the flow of the coating liquid in the surface direction is hindered on the surface, causing fine irregularities on the surface. Therefore, it is very effective for forming a uniform coating film.

  First, the principle of edge bead formation will be described with reference to FIGS.

  FIG. 3 is a part of a cross-sectional view of an ideal film shape when a coating solution is applied using a slit coating method or the like.

  In FIG. 3, 1 is a substrate, 3 is a coating film, and 7 is a coating liquid film. FIG. 3A is a cross-sectional view of the coating liquid film 7 immediately after coating, and FIG. 3B is a cross-sectional view of the coating film 3 obtained by coating the coating liquid film 7 by drying, chemical reaction, or physical reaction. . In the coating liquid film 7, volatile components are evaporated by drying or the like to form a coating film to form the coating film 3, so that the film thickness of the coating film 3 is significantly thinner than the coating liquid film 7.

  When the coating liquid 2 is applied onto the substrate 1, the upper surface of the solid substrate 1, the coating liquid 2 as a liquid, and the gas surrounding them are balanced by their interfacial tensions. In consideration of gravity, the state shown by the arrows (4a, 4b, 4c) in FIG. 4 is obtained.

  As shown by the arrow 4a in FIG. 4, the liquid (coating liquid 2) is stabilized with a contact angle of 90 degrees or less with respect to a solid (substrate 1) having a general surface energy.

  Therefore, at the end of the coating liquid film 7, a force is applied in the direction of the arrows (5a, 5b, 5c) shown in FIG. However, in consideration of gravity, the force applied to the side surface of the coating liquid film 7 is deformed and stabilized so as to have an inward slope. That is, as shown in FIG. 5B, the direction is stabilized in the direction indicated by the arrow 5d having a certain inclination from the direction indicated by the arrow 5a. At that time, if the volume of the contact surface of the coating liquid film 7 with the substrate 1 does not change, the coating liquid slides outward.

  Next, the process of drying the actual liquid film as it is will be described with reference to FIG.

FIG. 6A schematically shows the dry state of the coating liquid film 7 in FIG. As shown by the arrows in the figure, the coating liquid film 7 is dried by evaporation of the solvent from the surface and end portions. In this case, the drying proceeds from the surface and end of the portion indicated by the broken-line circle, and the solute content is higher than that of the other portions. as a result,
As shown in FIG. 6B, the surface tension of the coating liquid film 7 in this portion is higher than that in other portions, and the movement of the substance in the coating liquid film 7 occurs due to the imbalance of the surface tension. . As a result, a singular point having a shape as shown in FIG. 6C is formed around this portion, and further, the dryness of this portion progresses and an edge bead grows. As shown in FIG. 6D, the coating liquid film 7 becomes the coating film 3, and the movement of the liquid from the end and inside of the coating film 3
An edge bead 4 is formed, and a hollow portion 5 having a thickness smaller than the average thickness is formed around the edge bead 4.

  Next, the drying method of the coating liquid film and the principle that edge beads are reduced in the coating film forming method according to the present invention will be described with reference to FIG.

  First, as shown in FIG. 7A, as a means for removing at least a part of the solvent component in the coating liquid 2 from the coating liquid film 7 after the coating liquid 2 is extended, as shown in FIG. The drying accelerator 24 is brought into contact with the solvent to absorb the solvent.

As shown in FIG. 7C, the solvent contained in the coating liquid 2 is absorbed by the drying accelerator 24,
The fluidity of the coating liquid film 7 is lost, and the coating liquid film 7 becomes a gel-like coating film 8. Unevenness of the film due to mass transfer accompanying flow is unlikely to occur.

  Further, the unevenness on the surface of the coating film caused by the Benard cell is caused by the Marangoni flow due to the surface tension difference on the surface of the coating liquid film 7, but according to the method of the present invention, the surface of the coating liquid film is A surface tension difference does not appear because it is covered with an object such as the solvent absorber 8. Further, since the surface of the coating liquid film 7 does not become a free surface but is in contact with the solvent absorber 8, shear stress is generated, and this also inhibits the flow in the coating liquid film 7.

  Due to such a principle, compared to the general drying method described above, the drying method according to the present invention is less likely to cause edge beads 4 and fine irregularities on the surface of the coating film 3, and a flat film can be easily formed. Can get to.

  After the absorption by the solvent absorber 8 is sufficiently performed, the solvent absorber 8 is removed as shown in FIG. 7D, and if there is any remaining solvent, it is removed by some method. For example, as shown in FIG. 7E, the substrate 1 is placed in an oven, dried by heating, and taken out as shown in FIG. 7F, whereby a coating film is finally formed.

As a means for removing at least a part of the solvent in the coating solution, a sheet-like object capable of separating the solvent and the solute, such as a reverse osmosis membrane, can be used in addition to the solvent absorber. in this case,
After the film is in contact with the coating liquid film, it is necessary to remove the solvent that exudes from the back of the film by some means. As a removal method at this time,
In addition to absorption by the absorber, drying acceleration by adjusting the atmosphere such as flow of dry air or reduced pressure is used. Other methods may also be used.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a perspective view of a coating mechanism for explaining a first embodiment of the present invention. In the figure, 1 is a substrate made of a thin metal plate, glass, silicon, resin or the like, 9 is a substantially semicircular bead formed when the coating liquid 2 comes into contact with the substrate 1, and 7 is the coating liquid 2 on the substrate 1. It is the coating liquid film | membrane which shows the state applied in liquid form. Reference numeral 21 denotes an application head for applying the application liquid 2, which is movable relative to the substrate 1. Reference numeral 22 denotes a head tip portion that is a coating liquid discharge portion of the coating head 21.

  Reference numeral 24 denotes a drying accelerator made of elastomer, silicone rubber, reverse osmosis membrane or the like, 25 denotes a drying accelerator support, and 26 denotes a pressing roller for the drying accelerator 24.

  FIG. 2 is a sectional view of the coating mechanism for explaining the process of the first embodiment of the present invention.

First, in FIG. 2A, the coating liquid 2 is introduced into the coating head 21, and the substrate 1 is set on a stage (not shown). Next, in FIG. 2B, the coating liquid 2 is discharged from the coating head 21 to form a substantially semicircular bead 9 between the head tip 22 and the substrate 1. Next, in FIG. 2C, the coating head 21 is scanned in the direction indicated by the arrow in a state where the coating liquid 2 is discharged, and the formation of the coating liquid film 7 on the substrate 1 is started. The drying accelerator support 25 is moved following the coating liquid film 7 formed by scanning the coating head 21,
The drying accelerating body 24 is placed in close contact with the surface of the coating liquid film 7. At this time, a constant pressure is applied from the back surface of the drying accelerator 24 by the pressing roller 26 so that the drying accelerator 24 is in close contact with the coating liquid film 7.

Next, in FIG. 2D, the coating head 21 is further scanned, and the coating liquid film 7 is formed in a predetermined region of the substrate 1 while simultaneously operating the drying accelerator 24 and the pressing roller 26 on the surface of the coating liquid film 7. To do. Next, in FIG. 2E, the discharge of the coating liquid 2 from the coating head 21 is finished, the coating head 21 is separated from the substrate 1, and the drying accelerator 24 and the presser are applied to the entire area on the coating liquid film 7. End the operation of roller 26,
Application is complete.

Next, in FIG. 2 (f), the pressing roller 26 is separated from the back surface of the drying accelerating body 24, and the drying accelerating body 24 is peeled off from the application liquid starting point on the coating liquid film 7. As shown in FIGS. 2 (g) to 2 (h), the entire film is peeled off to obtain a coating film 3 having lost its fluidity as shown in FIG. 2 (i).
(Second Embodiment)
FIG. 8 is a perspective view of a coating mechanism for explaining a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same member as FIG. 1 which shows 1st Embodiment, The description is abbreviate | omitted.

  In the figure, reference numeral 30 denotes a decompression chamber, which promotes the removal of the solvent by pressing against the back surface of the drying accelerator 24 and reducing the pressure. In the figure, 31 is an intake port and 32 is an exhaust port. When the decompression chamber 30 operates, the exhaust port 32 is forcibly exhausted, and at the same time, air, dry air, hot dry air, etc. are introduced from the intake port 31 little by little. This facilitates drying without creating a stagnation of solvent gas in the decompression chamber 30. Further, the lower surface of the decompression chamber 30, 33 in the figure, is a decompression drying surface, which is composed of, for example, a fine mesh or a porous plate, and has a structure capable of intake from this surface.

  FIG. 9 is a cross-sectional view showing a part of the coating mechanism for explaining the process of the second embodiment of the present invention.

First, in the second embodiment, the first half of the process is performed in the same manner as in the first embodiment. In other words, the process is exactly the same as that of the first embodiment shown in FIGS. Next, as shown in FIG. 9A, after the coating head 21 and the pressing roller 26 are moved from the drying accelerator 24, the vacuum drying surface 33 of the vacuum chamber 30 in FIG. The drying accelerator 24 is pressed against the back surface of the membrane 7. Thereafter, the intake port 31 provided on the side surface of the decompression chamber 30 is slightly opened, and exhaust is started from the exhaust port 32 installed on the opposite side to decompress the interior of the decompression chamber.

After reducing the pressure for a certain period of time and the coating liquid film 7 is sufficiently dried, the chamber 30 is removed from the back surface of the drying accelerator 24, and again in the same manner as in the process of the first embodiment, FIGS. As described above, the drying accelerator 24 is peeled off from the surface of the coating liquid film 7. As described in the first embodiment, if there is a residual solvent,
For example, the solvent is removed by a method such as heating, and the drying is completed.

Thus, the drying of the coating liquid 2 is promoted by covering the surface of the coating liquid film 7 with the drying accelerator 24 and removing the solvent that permeates through the drying accelerator 24 from the back surface of the drying accelerator 24. By losing the fluidity at an early stage later, the movement of the coating liquid in the surface is suppressed, and the edge bead generated as a result of the movement and the minute unevenness of the surface generated as a result of the periodic flow can be reduced.
[Example 1]
In this example, the coating film 3 was formed on the substrate 1 by using the coating apparatus described in FIG. 1 and the coating film forming method described in FIG. As the substrate 1, a glass substrate having a size of 100 mm × 100 mm and a thickness of 1.1 mm was used. The coating solution 2 was a PMMA cyclohexanone solution (solvent content 55 parts by weight). The drying accelerator 24 is made of 1.5 mm thick silicone rubber (no filler) and is placed behind the coating head 21 as shown in FIG. 1 and applied immediately after the coating liquid 2 is applied from the coating head 21. The surface of the liquid film 7 can be covered.

  The coating liquid film 7 is coated so that the width × length is 30 mm × 50 mm and the thickness as the liquid film is about 20 μm. At the same time, the drying accelerator 24 and the drying accelerator support disposed behind the coating head 21 are supported. The tool 25 and the pressing roller 26 were moved so that the surface of the coating liquid film 7 was in close contact with the drying accelerator 24 and covered. After the discharge of the coating liquid 2 from the coating head 21 was stopped, the drying accelerator 24 was gently peeled off from the surface of the coating liquid film 7 from the coating start portion.

  At this time, the fluidity of the coating liquid film 7 was lost and became a gel. Thereafter, the substrate was heated on a hot plate at 60 ° C. under the condition of proxy 0.5 mm for 15 minutes. Thereafter, the positions and heights of the apexes of the edge beads 4 formed on both sides of the coating film 3 formed on the substrate 1 and the distance from the periphery to the flat portion were measured. Table 1 shows the average measurement results for 10 measurement results.

Further, this coating / drying operation was performed 10 times every 4 minutes, and the amounts of the coating film 3 applied to the 10th substrate were measured in the same manner and are shown in Table 1.
[Example 2]
In this example, the coating mechanism described in FIG. 8 was used, and the coating film 3 was formed on the substrate 1 using the coating process described in FIGS. 9 and 2. The drying accelerator 24 used in this example is the same material as in Example 1,
The thing of thickness 350micrometer was used. The substrate and the coating solution were the same as in Example 1, and the coating area and thickness were applied under the same conditions as in Example 1.

  In this way, the substrate on which the coating film 3 was applied was heated on a hot plate of 0.5 mm proxy and 60 ° C. for 15 minutes in the same manner as in Example 1. The film thickness profile in the width direction of the formed coating film was measured, and the height and position of the edge beads generated on both sides in the coating width direction of the coating film 3 and the distance to the flat portion were measured. Table 1 shows the average measurement results for 10 measurement results.

Further, as in Example 1, this coating / drying operation was repeated 10 times every 4 minutes, and each amount was measured and shown in Table 1.
<Comparative Example 1>
A similar coating film was formed using the same coating apparatus and coating film forming method as in Example 1. However, the drying accelerator and the pressing roller used in Example 1 were not operated, and after the coating liquid film was formed, the film was directly dried on the hot plate under the same conditions as in Example 1. About this coating film, the film thickness of the width direction was measured and the height to a bead, a position, and the distance to a flat part were measured. Table 1 shows the average measurement results for 10 measurement results.

表１に示した通り、実施例１及び２と従来例１とを比較すると、実施例１及び２は比較例１に比べ塗布膜周辺部分の膜荒れの範囲、エッジビードが小さいことが分かる。

As shown in Table 1, when Examples 1 and 2 are compared with Conventional Example 1, it can be seen that Examples 1 and 2 have a smaller film roughness range and edge bead around the coating film than Comparative Example 1.

Also, when the drying accelerator absorbs the solvent and the drying proceeds, if it is absorbed and used for a long time, the solvent will accumulate in the absorber and the amount of absorption when it comes into contact with the coating liquid film will be different. For,
The process is not stable.

  Examples of embodiments of the present invention are shown below.

Embodiment Example 1
In a coating film forming method in which a coating liquid is stretched and fixed on a substrate to form a coating film, a sheet-like object is brought into contact with the coating surface during or after the coating liquid is stretched, and at least partly from the coating liquid The coating film formation method characterized by removing fluidity and losing fluidity.

Embodiment Example 2
The removal of at least a part of the coating liquid is performed by contacting a sheet-like object, and a part of the compound in the coating liquid is absorbed and lost on the sheet side. Forming method.

Embodiment Example 3
2. The coating film forming method according to Embodiment 1, wherein the sheet-like object is made of silicone rubber.

(Embodiment example 4)
The method for forming a coating film according to Embodiment 1 is characterized in that at least a part of the coating solution is removed by contacting a sheet-like object so that a part of the compound in the coating solution is separated by the sheet.

  (Embodiment Example 5) Any one of Embodiment Examples 1 to 4 is characterized in that the method of extending and fixing the coating liquid uses a slit coating method in which the coating liquid is applied by being discharged from a slit-like nozzle. The coating film formation method of description.

(Embodiment example 6)
A coating apparatus that discharges a coating liquid from a coating head, and extends and fixes the coating liquid on a substrate. The coating apparatus includes means for removing at least a part of the coating liquid.

Embodiment Example 7
The coating apparatus according to embodiment 6, wherein the means for removing at least a part of the coating liquid includes an operation of bringing a sheet-like object into contact with the surface of the coating liquid during or after stretching.

(Embodiment Example 8)
The means for removing at least a part of the solution described in Embodiment 7 has a mechanism for forcibly removing a part of the compound contained in the coating liquid through the sheet-like object. The coating apparatus according to Embodiment 7 which is characterized.

  (Embodiment Example 9) A coating film formed product formed by using the coating film forming method described in any of Embodiment Examples 1 to 5.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a method for forming a coating film having necessary flatness or unevenness on a substrate in components such as an image display device and an inkjet recording device, a printed circuit board, and other device components. It is.

It is a perspective view which shows the coating device of 1st Embodiment in this invention. It is sectional drawing explaining the coating film formation method using the coating device shown in FIG. It is sectional drawing explaining the state which the coated material dries. It is sectional drawing explaining the state of the ideal coating liquid film. It is sectional drawing explaining the state of the coating liquid film. It is sectional drawing explaining the principle of the dry state of a coating liquid film. It is sectional drawing explaining the principle of the dry state of the coating liquid film of this invention. It is a perspective view which shows the coating device of the 2nd Embodiment of this invention. It is sectional drawing explaining the coating film formation method using the coating device shown in FIG. It is sectional drawing explaining the coating film formation method of the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Coating liquid 3 Coating film 4 Edge bead 5 Dimple part 6 Flat part 7 Coating liquid film 8 Gel-like coating film 9 Bead 20 Substrate support 21 Coating head 22 Head tip part 23 Coating liquid supply dispenser 24 Drying acceleration body 25 Drying acceleration Body support 26 Pressing roller 27 Oven 30 Depressurization chamber 31 Inlet port 32 Exhaust port 33 Depressurized drying surface

Claims (1)

In a coating film forming method of extending and fixing a coating liquid to a substrate and forming a coating film,
A method for forming a coating film, comprising: bringing a sheet-like object into contact with a coating surface during or after stretching of the coating solution, and removing at least part of the coating solution to lose its fluidity.

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