JP2010264426A - Droplet coating method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detection accuracy of a landing area of each droplet discharged from each nozzle and dripped on a substrate, even there is variance in the contact angle of a liquid repellent film formed on the surface of an inspection substrate with a coating liquid and further, to adjust discharge quantity of each nozzle due to individual difference of each nozzle. <P>SOLUTION: In a droplet coating method, the droplet Ei discharged from each of a plurality of nozzles Ni is dripped on a substrate K, and the image of each dripped droplet Ei is detected. Then, in a state where the substrate K is turned by 180° around an axis orthogonal to the surface with respect to a coating head 14, the droplet Ei discharged from each of the plurality of nozzles Ni is again dripped on the substrate K, thereby detecting the image of each dripped droplet Ei. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a droplet coating method and apparatus.

  As a liquid droplet application device for ink or the like, there is a device that drops liquid droplets discharged from each of a plurality of nozzles of a coating head onto a substrate as described in Japanese Patent Application Laid-Open No. H10-228707. The coating head includes a piezoelectric element corresponding to each nozzle, and discharges a coating liquid from each nozzle in accordance with application of a driving voltage to each piezoelectric element. In a coating head used for forming a thin film such as an alignment film or a color filter, it is required that the discharge amount of the coating liquid from each nozzle be uniformly adjusted in order to form a film having a uniform thickness. However, even if the same drive voltage is applied to each piezoelectric element due to individual differences among the nozzles, individual differences among the piezoelectric elements, etc., the discharge amount of the coating liquid from each nozzle is not necessarily the same.

  Therefore, in the conventional technology, the discharge amount of the coating liquid from each nozzle is detected, and the applied voltage of each piezoelectric element is adjusted based on the detection result, so that the discharge amount of the coating liquid from each nozzle is the same. It is adjusted so that

  At this time, in the prior art, the amount of the coating liquid discharged from each nozzle is set to the image of each droplet discharged from each nozzle and dropped onto the inspection substrate, in other words, the landing area (projected area) of each droplet. )

  Furthermore, in the prior art, in order to improve the detection accuracy of the landing area of each droplet discharged from each nozzle and dropped on the inspection substrate, a liquid repellent film such as a fluororesin is provided on the surface of the inspection substrate. It is formed to clarify the landing shape of each droplet.

JP 2004-136582 JP

  In the prior art, the landing shape of each droplet described above is detected on the assumption that the contact angle with the coating liquid is uniform over the entire liquid-repellent film on the surface of the inspection substrate.

  However, the contact angle with the coating liquid of the liquid repellent film formed on the surface of the inspection substrate varies depending on the location (region) on the substrate. When the contact angle varies in each region of the inspection substrate, even if the application amount is the same, the projected area of the landed coating liquid is small in the region where the contact angle is large compared to the region where the contact angle is small. When such an inspection substrate is used, an error resulting from contact angle variation is included in the landing area detection result, and it becomes difficult to uniformly adjust the discharge amount between the nozzles.

  The problem of the present invention is that the landing area of each droplet discharged from each nozzle and dropped onto the substrate even if there is variation in the contact angle with the coating liquid of the liquid repellent film formed on the surface of the inspection substrate Is to adjust the discharge amount of each nozzle resulting from individual differences of each nozzle.

  According to the first aspect of the present invention, the liquid droplets discharged from each of the plurality of nozzles of the coating head are dropped on the substrate on which the liquid repellent film is formed, and based on the image of each liquid droplet dropped on the substrate. Then, in the droplet application method for determining the discharge amount of the droplets from each nozzle, the droplets discharged from each of the plurality of nozzles are dropped on the substrate, and after detecting the image of each dropped droplet, In a state where the substrate is rotated 180 degrees around the axis perpendicular to the surface of the substrate with respect to the coating head, droplets discharged from each of the plurality of nozzles are again dropped onto the substrate, and each dropped droplet The image is detected.

  According to a second aspect of the present invention, in the first aspect of the present invention, the average value of the respective discharge amounts obtained based on the images of the respective droplets dropped on the substrate from the same nozzle before and after the rotation of the substrate by 180 degrees. Is the discharge amount of droplets from the nozzle.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the central axis of 180 ° rotation of the substrate is made to coincide with the center of the arrangement of the plurality of nozzles in the coating head.

  According to a fourth aspect of the present invention, the liquid droplets discharged from each of the plurality of nozzles of the coating head are dropped on the substrate on which the liquid repellent film is formed, and based on an image of each liquid droplet dropped on the substrate. In the droplet coating apparatus for determining the droplet discharge amount from each nozzle, a detection unit for determining the droplet discharge amount from each nozzle based on the image of each droplet dropped on the substrate, The detection unit drops droplets discharged from each of the plurality of nozzles onto the substrate, detects an image of each dropped droplet, and then centers the substrate perpendicular to the surface of the coating head with respect to the coating head. In this state, the liquid droplets discharged from each of the plurality of nozzles are again dropped on the substrate while being rotated 180 degrees, and an image of each dropped liquid droplet is detected.

  According to a fifth aspect of the present invention, in the fourth aspect of the invention, each of the detection units is obtained based on an image of each droplet dropped on the substrate from the same nozzle before and after the substrate is rotated 180 degrees. The average value of the discharge amount is set as the discharge amount of droplets from the nozzle.

  According to a sixth aspect of the present invention, in the fourth or fifth aspect of the present invention, the center axis of the substrate rotated 180 degrees is made to coincide with the center of the arrangement of the plurality of nozzles in the coating head.

  According to the present invention, the liquid-repellent film coating liquid formed on the surface of the inspection substrate by detecting the image of each droplet dropped on the substrate from the same nozzle before and after the 180-degree rotation of the substrate. Even if the contact angle varies, the detection accuracy of the landing area of each droplet discharged from each nozzle and dropped on the substrate is improved, and as a result, the discharge amount of each nozzle due to individual differences of each nozzle Can be adjusted.

FIG. 1 is a schematic view showing a droplet applying apparatus. FIG. 2 is a schematic diagram illustrating a detection state by the detection unit. FIG. 3 is a schematic diagram showing the contact angle distribution of the substrate and the landing area of the droplet. FIG. 4 is a schematic diagram showing the principle of measuring the discharge amount of each nozzle according to the present invention.

  As shown in FIG. 1, the droplet applying apparatus 10 has a moving table 11 on which a substrate K, which is an object to be applied, is placed in a horizontal state (in FIG. 1, along the X-axis direction and the Y-axis direction perpendicular thereto). A Y-axis moving mechanism 12 that holds the moving table 11 and moves it in the Y-axis direction, an X-axis moving mechanism 13 that moves the moving table 11 in the X-axis direction via the Y-axis moving mechanism 12, Each of the plurality of nozzles Ni (N 1, N 2,...) Of each coating head 14 has a plurality of coating heads 14 adjacent to each other for discharging a coating liquid such as ink as droplets toward the substrate K on the table 11. A droplet Ei (E1, E2,...) Discharged from the substrate is applied to the substrate K. The Y-axis moving mechanism 12, the X-axis moving mechanism 13, and each coating head 14 of the moving table 11 are controlled by the control unit 15.

  That is, the moving table 11 is stacked on the Y-axis moving mechanism 12 and is provided so as to be movable in the Y-axis direction. The moving table 11 is moved in the Y-axis direction by the Y-axis moving mechanism 12. Although the substrate K is placed on the moving table 11 by its own weight, the present invention is not limited to this. For example, in order to hold the substrate K, a mechanism such as an electrostatic chuck or a suction chuck is provided. Also good. At the end of the moving table 11, a discharge stabilizing portion 11 a for stabilizing the discharge of each coating head 14 is provided. The discharge stabilizing unit 11a includes a dummy receiving tray for each coating head 14, a wipe blade for wiping the discharge surface of each coating head 14, and the like.

  The Y-axis moving mechanism 12 is a mechanism that guides and moves the moving table 11 in the Y-axis direction. The Y-axis moving mechanism 12 is electrically connected to the control unit 15, and its driving is controlled by the control unit 15. As the Y-axis moving mechanism 12, for example, a linear motor moving mechanism using a linear motor as a driving source, a feed screw moving mechanism using a motor as a driving source, or the like is used.

  The X-axis moving mechanism 13 is a mechanism that guides and moves the Y-axis moving mechanism 12 in the X-axis direction. The X-axis moving mechanism 13 is electrically connected to the control unit 15, and its driving is controlled by the control unit 15. As the X-axis moving mechanism 13, for example, a linear motor moving mechanism using a linear motor as a driving source, a feed screw moving mechanism using a motor as a driving source, or the like is used.

  The coating head 14 is an inkjet head that discharges coating liquid supplied from a liquid tank (not shown) that stores coating liquid such as ink as droplets Ei from a plurality of nozzles Ni. The coating head 14 incorporates a plurality of piezoelectric elements (not shown) corresponding to the plurality of nozzles Ni for discharging droplets. The nozzles Ni are formed on the discharge surface in a straight line at a predetermined pitch (interval). For example, the number of nozzles Ni is about several tens to several hundreds, the diameter of the nozzles Ni is about several μm to several tens of μm, and the pitch of the nozzles Ni is about several tens μm to several hundreds of μm. .

  The coating head 14 is electrically connected to the control unit 15, and its driving is controlled by the control unit 15. The coating head 14 ejects droplets (ink droplets) Ei from each nozzle Ni in response to application of a driving voltage to each piezoelectric element. Here, the coating liquid has volatility. This coating solution is composed of a solute that remains as a residue on the substrate K and a solvent that dissolves (disperses) the solute. For example, the ink that is the coating liquid is composed of various components such as a pigment, a solvent (ink solvent), a dispersant, and an additive.

  The coating head 14 is supported by a rotation mechanism (not shown) so as to be rotatable in the θ direction (rotation direction along the XY plane in FIG. 1). The coating head 14 is tilted by a predetermined tilt angle with respect to the relative movement direction of the relatively moving substrate K by the rotation mechanism, and coating is performed in this state. When coating is performed on the substrate K that relatively moves in the Y-axis direction, the droplet coating pitch in the X-axis direction can be adjusted by changing the tilt angle of the coating head 14. In addition, the application pitch in the Y-axis direction can be adjusted by changing the droplet discharge frequency (discharge timing).

  The control unit 15 includes a microcomputer that centrally controls each unit, and a storage unit that stores application information related to application, various programs, and the like (none of which are shown). The application information includes a predetermined application pattern such as a dot pattern, an inclination angle of the application head 14, information regarding the ejection frequency of the application head 14, and the moving speed of the substrate K. As the application information, application information for manufacturing application and application information for inspection application (including a pattern for inspection and a pattern for forming a solvent atmosphere) are stored in the storage unit.

  However, since the droplet applying apparatus 10 adjusts the discharge amount of the plurality of nozzles Ni of the coating head 14 to be uniform, the droplet Ei discharged from each of the nozzles Ni of the coating head 14 is liquid repellent. The amount of droplet Ei discharged from each nozzle Ni is obtained based on the image of each droplet Ei dropped on the inspection substrate K on which the film is formed. That is, the droplet applying device 10 includes a detection unit 16 that obtains the discharge amount of the droplet Ei from each nozzle Ni of the coating head 14 based on the image of each droplet Ei dropped on the inspection substrate K. As shown in FIG. 2, the detection unit 16 includes an imaging unit 16A, an arithmetic processing unit 16B that also serves as an image processing unit, and a display unit 16C.

  The imaging unit 16A includes an imaging camera that images each droplet Ei landed on the substrate K. The imaging unit 16A is electrically connected to the arithmetic processing unit 16B and the control unit 15, and the driving thereof is controlled by the control unit 15, and the captured image of each droplet is transmitted to the arithmetic processing unit 16B. For example, a CCD (Charge Coupled Device) camera or the like is used as the imaging unit 16A.

  The arithmetic processing unit 16B, based on the image (detection result) of each droplet Ei transmitted from the imaging unit 16A, each landing area (projected area) Si (S1, S1) of each droplet Ei that has landed on the substrate K. S2, ...) is obtained. Further, the arithmetic processing unit 16B calculates the ejection amount of the droplet Ei from each nozzle Ni based on the calculated landing area of each droplet Ei, and transmits the result to the control unit 15. Here, the discharge amount is calculated from the relational expression between the landing area of the droplet Ei and the discharge amount (drop amount). For example, the relationship between the droplet landing area and the discharge amount can be expressed by a linear expression, which can be derived from experimental results. The relational expression is stored in a storage unit included in the arithmetic processing unit 16B. For example, a computer or the like is used as the arithmetic processing unit 16B.

  The display unit 16 </ b> C is a display device that displays various images such as captured images of each droplet. The display unit 16C is electrically connected to the arithmetic processing unit 16B. For example, a liquid crystal display or a CRT display is used as the display unit 16C.

  When the controller 15 receives the ejection amount of the droplet Ei from each nozzle Ni of the coating head 14 obtained by the arithmetic processing unit 16B of the detection unit 16, the ejection amount of each nozzle Ni of the coating head 14 is set to the target ejection. The piezoelectric element corresponding to each nozzle Ni is driven so as to match the amount. That is, the applied voltage is adjusted based on the relationship (voltage coefficient) between the voltage applied to the piezoelectric element of each nozzle Ni of the coating head 14 and the ejection amount. Thereby, the discharge amount of each nozzle Ni of the coating head 14 is adjusted to be uniform.

  By the way, when a liquid-repellent film made of a fluororesin or the like is formed on the surface of the inspection substrate K like the inspection substrate K used in the present embodiment, the film formation is usually performed by sputtering or vacuum evaporation. A device is used. In such a film forming apparatus, a substrate is usually housed in a processing chamber for film formation. On the other hand, in the processing chamber, the film forming material moves from one material gas inlet on the ceiling side toward one exhaust port on the floor side. For this reason, on the surface of the substrate in the processing chamber, a difference occurs in the distance from the gas introduction port of the film forming material. Specifically, the distance between the substrate and the film introduction material gas introduction port gradually increases from one end close to the film formation material gas introduction port to the other end.

  In the formation of a liquid repellent film using such a film forming apparatus, if there is a difference in the distance from the gas introduction port of the film forming material, the gas introduction of the film forming material is performed in the formed liquid repellent film. The portion closer to the mouth tends to have a larger contact angle than the portion farther away. Therefore, when a liquid repellent film is formed on the substrate using a film forming apparatus by sputtering or vacuum deposition, the coating liquid is applied from the region M1 on one end A side to the region M3 on the other end B side of the substrate. The contact angle tends to increase or decrease linearly so that the contact angle gradually decreases. That is, as shown in FIG. 3, the coating head 14 includes three nozzles N1 to N3 arranged in a line, and each of the nozzles N1 to N3 has three regions M1 to M3 on the inspection substrate K. When the droplets E1 to E3 are made to land on each of these, the areas M1, M2, and M3 of the inspection substrate K are in contact with each other compared to the area M3 having a small contact angle even if the application amount is the same. When M1 has a large angle, the projected area of the landed coating liquid becomes small (S1 <S2 <S3). When such an inspection substrate K is used, the detection results of the landing areas S1, S2, and S3 of the droplets E1 to E3 ejected from the nozzles M1 to M3 include errors due to contact angle variations. Therefore, it becomes difficult to uniformly adjust the discharge amount between the nozzles.

  Therefore, the droplet applying apparatus 10 is discharged from each nozzle Ni of the coating head 14 and has an inspection substrate even if the contact angle of the liquid repellent film formed on the surface of the inspection substrate K varies. In order to improve the detection accuracy of the landing area of each droplet Ei dripped onto K, and to make it possible to adjust the discharge amount of each nozzle Ni due to individual differences of each nozzle Ni, the following (1) to (4) ) In this order (FIG. 4).

  (1) Droplets E1 to E3 discharged from each of the three nozzles N1 to N3 of the coating head 14 are dropped onto the inspection substrate K (substrate K1 in FIG. 4). The droplets E1 to E3 dropped on the inspection substrate K (substrate K1 in FIG. 4) are individually imaged by the imaging unit 16A of the detection unit 16. Each captured image is sent to the arithmetic processing unit 16B, and the arithmetic processing unit 16B detects the landing area of each dropped droplet E1 to E3.

  The droplet E1 discharged from the nozzle N1 on one end side of the coating head 14 onto the inspection substrate K (substrate K1 in FIG. 4) lands on the large contact angle region M1 on the one end A side of the inspection substrate K and is small. The landing area S1a is exhibited.

  The droplet E3 discharged from the nozzle N3 on the other end side of the coating head 14 onto the inspection substrate K (substrate K1 in FIG. 4) enters the small contact angle region M3 on the other end B side of the inspection substrate K. Landing and presents a large landing area S3b.

  (2) The inspection substrate K is rotated 180 degrees with respect to the coating head 14 around an axis orthogonal to the surface thereof (substrate K2 in FIG. 4).

  The central axis of 180 ° rotation of the inspection substrate K is matched with the center of the arrangement of the three nozzles N1 to N3 in the coating head 14. In this example, the position of the nozzle N2 is exactly the center.

  (3) Droplets E1 to E3 discharged from each of the three nozzles N1 to N3 of the coating head 14 are dropped onto the inspection substrate K (substrate K2 in FIG. 4). The droplets E1 to E3 dropped on the inspection substrate K (substrate K2 in FIG. 4) are individually imaged by the imaging unit 16A of the detection unit 16. Each captured image is sent to the arithmetic processing unit 16B, and the arithmetic processing unit 16B detects the landing areas of the dropped liquid droplets E1 to E3.

  The droplet E1 discharged from the nozzle N1 on one end side of the coating head 14 onto the inspection substrate K (substrate K2 in FIG. 4) lands on the small contact angle region M3 on the other end B side of the inspection substrate K. Presents a large landing area S1b.

  The droplet E3 discharged from the nozzle N3 on the other end side of the coating head 14 onto the inspection substrate K (substrate K2 in FIG. 4) enters the large contact angle region M1 on the other end A side of the inspection substrate K. Landing and presents a small landing area S3a.

  (4) The arithmetic processing unit 16B of the detection unit 16 is placed on the inspection substrate K from the same nozzle, for example, the nozzle N1, before and after the 180-degree rotation of the inspection substrate K according to the above (1) and (3). Based on the captured image of the dropped droplet E1, the landing areas (projected areas) S1a and S1b of the droplet E1 are obtained. Further, the ejection amounts T1a and T1b based on the landing areas S1a and S1b of the droplet E1 are obtained. Ask.

  Further, the arithmetic processing unit 16B of the detection unit 16 obtains an average value T1 of the two discharge amounts T1a and T1b, and uses this T1 as the discharge amount of the droplet E1 discharged from the nozzle N1.

  The discharge amounts of the droplets E2 and E3 discharged from the other nozzles N2 and N3 of the coating head 14 are also determined in the same manner as in the above (1) to (4).

According to the present embodiment, the following operational effects can be obtained.
(a) When the liquid repellent film is formed on the substrate K by using a film forming apparatus by sputtering or vacuum evaporation as in the inspection substrate K of the present embodiment, the other end from the region M1 on the one end A side of the substrate K There is a tendency that the contact angle with the coating liquid gradually increases or decreases linearly over the region M3 on the B side. On the other hand, in the present invention, the droplet Ei discharged from each of the plurality of nozzles Ni of the coating head 14 is dropped on the substrate K, and after detecting the image of each dropped droplet Ei, the coating head 14 is detected. In the state where the substrate K is rotated 180 degrees around the axis orthogonal to the surface thereof, the droplets Ei discharged from each of the plurality of nozzles Ni are dropped again on the substrate K, and each dropped It was decided to detect the image of the droplet Ei. Therefore, the picked-up image of the droplet Ei discharged from the nozzle Ni on one end side of the coating head 14 lands on the large contact angle region M1 on the one end A side of the substrate K before rotating 180 degrees to reduce the small landing area S1a. In addition, it is landed on the small contact angle region M3 on the other end B side of the substrate K after being rotated 180 degrees to exhibit a large landing area S1b. The difference in landing area (S1a, S1b) of two droplets E1 ejected from the same nozzle N1 is based only on a linear change in contact angle from one end A to the other end B of the substrate K. By taking the average value of the landing areas (S1a, S1b) of the two droplets E1, the discharge amount of the nozzle N1 due to the individual difference of the nozzle N1, which eliminates the variation in the contact angle of the substrate K, is measured. To get.

  (b) Before and after the rotation of the substrate K by 180 degrees, based on the captured image of each droplet Ei dropped on the substrate K from the same nozzle Ni, in other words, based on the landing area (S1a, S1b) of each droplet Ei. By determining the average value of the respective discharge amounts as the discharge amount of the droplet Ei from the nozzle Ni, the discharge of the nozzle Ni due to the individual difference of the nozzle Ni that eliminates the variation in the contact angle of the substrate K is eliminated. The amount can be measured. Thereby, the discharge amount of each nozzle Ni of the coating head 14 can be measured with high accuracy, and as a result, the discharge amount of each nozzle Ni can be adjusted uniformly.

  (c) By aligning the central axis of the 180 ° rotation of the substrate K with the center of the array of the plurality of nozzles Ni in the coating head 14, the droplets Ei discharged from each of the nozzles Ni are rotated about 180 °. Can be reliably landed on the substrate K. Using the same substrate K, the above steps (a) and (b) can be performed for all the nozzles Ni.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

  The present invention detects the image of each droplet dropped on the substrate from the same nozzle before and after 180 ° rotation of the substrate, thereby providing a coating solution for the liquid repellent film formed on the surface of the inspection substrate. Even if the contact angle varies, the detection accuracy of the landing area of each droplet discharged from each nozzle and dropped on the substrate is improved, and as a result, the discharge amount of each nozzle due to individual differences of each nozzle is adjusted. can do.

DESCRIPTION OF SYMBOLS 10 Droplet coating apparatus 14 Coating head 15 Control part 16 Detection part Ei Droplet K Substrate Ni Nozzle

Claims (6)

Drops discharged from each of the plurality of nozzles of the coating head are dropped on the substrate on which the liquid-repellent film is formed, and the liquid from each nozzle is based on the image of each droplet dropped on the substrate. In the droplet application method for determining the droplet discharge amount,
After the droplets discharged from each of the plurality of nozzles are dropped on the substrate and an image of each dropped droplet is detected,
With the substrate rotated 180 degrees around the axis perpendicular to the surface of the substrate with respect to the coating head,
A droplet applying method, wherein a droplet discharged from each of a plurality of nozzles is again dropped on a substrate, and an image of each dropped droplet is detected.   The average value of each discharge amount obtained based on the image of each droplet dropped from the same nozzle on the substrate before and after the rotation of the substrate by 180 degrees is defined as the droplet discharge amount from the nozzle. The droplet coating method described in 1.   The droplet coating method according to claim 1, wherein a central axis of 180 ° rotation of the substrate coincides with a center of an array of a plurality of nozzles in the coating head. Drops discharged from each of the plurality of nozzles of the coating head are dropped on the substrate on which the liquid-repellent film is formed, and the liquid from each nozzle is based on the image of each droplet dropped on the substrate. In a droplet application device that calculates the discharge amount of droplets,
Having a detection unit for determining the discharge amount of each droplet from each nozzle based on the image of each droplet dropped on the substrate;
The detection unit drops droplets discharged from each of the plurality of nozzles onto the substrate, detects an image of each dropped droplet, and then centers the substrate perpendicular to the surface of the coating head with respect to the coating head. A droplet coating apparatus that drops droplets ejected from each of the plurality of nozzles again on the substrate in a state rotated by 180 degrees, and detects an image of each dropped droplet.   The detection unit calculates the average value of each discharge amount obtained based on the image of each droplet dropped from the same nozzle on the substrate before and after the 180-degree rotation of the substrate. The droplet applying apparatus according to claim 4.   The droplet coating apparatus according to claim 4 or 5, wherein a central axis of 180 degree rotation of the substrate coincides with a center of an array of a plurality of nozzles in the coating head.

Images