TWO-AXIS SPIN COATING METHOD AND APPARATUS

Abstract

A modified technology of spin coating which is named Two-Axis spin coating is disclosed. The innovative Two-Axis spin coating apparatus is a rotary device that spins the substrate horizontally the same as conventional spin coaters while the whole horizontal spinning system can be rotated vertically. The vertical rotation of the substrate generates a vertical centrifugal force perpendicular to the surface of the substrate which allows the coating face with an elevated artificial gravity acceleration. The elevation of gravity acceleration adjusts and normalizes the local high and low surface tension stresses on the surface of the coated film. This elevation of gravity also increases the weight of coating elements artificially and obliges the wavy surface convex regions to flow toward the concave areas. The elevation of gravity also obliges the lighter probable air bubbles inside the layer, immediately before the coating surface skinning process, move toward the surface and drain out from the layer. The invention provides a method to level the layer's edge beads, level the coated surface, drain out probable micro sized air bubbles inside the layer and form denser film simultaneously.

Claims

1. A method or technology using Two-Axis spin coating innovation or Two-Axis spin coating innovated apparatus to form surface level thin and thick micrometer layers without edge beading and condensed film without air bubbling simultaneously comprising: (a) Adjusting the horizontal spinning chuck of the innovative apparatus so that the surface of the spinning horizontal chuck is parallel to the ground. (b) Placing a circular or rectangular substrate or any other shape in the center of the horizontal spinning chuck. (c) Sucking the substrate located in the center of the horizontal rotating chuck by turning on a vacuum pump. (d) Dispensing enough amount of a desired coating material over the top of the said sucked substrate in the center or near the center of the said horizontal spinning chuck. (e) Adjusting a horizontal rotational speed, acceleration rates, and rotation time of the said horizontal rotation which has been pre-determined. (f) Adjusting a vertical rotational velocity, rotational acceleration, and their duration for the vertical rotating of the entire said horizontal rotation system, in which the angle between the said vertical and horizontal rotation axis is 90 degrees. (g) Spinning the horizontal spinning chuck with the said pre-set values that will spread the deposited coating to the entire surface of said substrate. (h) Starting said vertical rotation with said pre-set values after a predetermined time has elapsed since the start of said horizontal rotation. (i) Continuing the both said horizontal and vertical rotations simultaneously for a predetermined period time where the said vertical rotation would generate a centrifugal force perpendicular to the surface of said substrate. (j) Holding the coated layer under the condition of elevated gravity acceleration which is created by the said centrifugal force for a predetermined duration of time. The surface of coated layer faces an airflow which is generated by the said vertical rotation. The said airflow while passing through the surface of the coated layer, the solvents of the coating are evaporated, and the layer becomes completely or partially dry. The said complete or partial drying under the effect of the said elevated gravity acceleration avoids the undesired spring back effect of the coating such as the edge beading or the wavy surface leveling. (k) Spinning off the said vertical rotation and consequently spinning off the said horizontal rotation of the substrate. (l) Stopping the said vertical rotation so that the surface of the said horizontal spinning chuck is held parallel to the ground. (m) Turning the said vacuum pump off and removing the said substrate from the said horizontal spinning chuck and preparing for the next processes.

2. A method or technology according to claim 1, wherein said coating materials are included various types of industrial and medical coatings such as photoresists, metallic, Non-Metallic, polymeric, organic, inorganic, and any industrial coatings useful in micro and Nanofabrication industries and not unlimited to any unspoken coatings.

3. A method or technology for coating micrometer and nanometer layers in which the rotation axis of the both said horizontal and vertical rotations are perpendicular to each other and the angle between them is 90 degrees comprising: (I) Coating micrometer and nanometer layers using the said vertical rotation perpendicular to said spinning chuck, a vertical centrifugal force perpendicular to the said substrate's surface is generated. (II) Coating micrometer and nanometer layers in which the said vertical centrifugal force perpendicular to the said horizontal spinning chuck artificially increase the gravitational acceleration. (III) Coating micrometer and nanometer layers which the said horizontal and the said vertical rotations can be performed independently or simultaneously.

1. A method or technology using Two-Axis spin coating innovation or Two-Axis spin coating innovated apparatus to form surface level thin and thick micrometer layers without edge beading and condensed film without air bubbling simultaneously comprising: (a) Adjusting the horizontal spinning chuck of the innovative apparatus so that the surface of the spinning horizontal chuck is parallel to the ground. (b) Placing a circular or rectangular substrate or any other shape in the center of the horizontal spinning chuck. (c) Sucking the substrate located in the center of the horizontal rotating chuck by turning on a vacuum pump. (d) Dispensing enough amount of a desired coating material over the top of the said sucked substrate in the center or near the center of the said horizontal spinning chuck. (e) Adjusting a horizontal rotational speed, acceleration rates, and rotation time of the said horizontal rotation which has been pre-determined. (f) Adjusting a vertical rotational velocity, rotational acceleration, and their duration for the vertical rotating of the entire said horizontal rotation system, in which the angle between the said vertical and horizontal rotation axis is 90 degrees. (g) Spinning the horizontal spinning chuck with the said pre-set values that will spread the deposited coating to the entire surface of said substrate. (h) Starting said vertical rotation with said pre-set values after a predetermined time has elapsed since the start of said horizontal rotation. (i) Continuing the both said horizontal and vertical rotations simultaneously for a predetermined period time where the said vertical rotation would generate a centrifugal force perpendicular to the surface of said substrate. (j) Holding the coated layer under the condition of elevated gravity acceleration which is created by the said centrifugal force for a predetermined duration of time. The surface of coated layer faces an airflow which is generated by the said vertical rotation. The said airflow while passing through the surface of the coated layer, the solvents of the coating are evaporated, and the layer becomes completely or partially dry. The said complete or partial drying under the effect of the said elevated gravity acceleration avoids the undesired spring back effect of the coating such as the edge beading or the wavy surface leveling. (k) Spinning off the said vertical rotation and consequently spinning off the said horizontal rotation of the substrate. (l) Stopping the said vertical rotation so that the surface of the said horizontal spinning chuck is held parallel to the ground. (m) Turning the said vacuum pump off and removing the said substrate from the said horizontal spinning chuck and preparing for the next processes.

2. A method or technology according to claim 1, wherein said coating materials are included various types of industrial and medical coatings such as photoresists, metallic, Non-Metallic, polymeric, organic, inorganic, and any industrial coatings useful in micro and Nanofabrication industries and not unlimited to any unspoken coatings.

3. A method or technology for coating micrometer and nanometer layers in which the rotation axis of the both said horizontal and vertical rotations are perpendicular to each other and the angle between them is 90 degrees comprising: (I) Coating micrometer and nanometer layers using the said vertical rotation perpendicular to said spinning chuck, a vertical centrifugal force perpendicular to the said substrate's surface is generated. (II) Coating micrometer and nanometer layers in which the said vertical centrifugal force perpendicular to the said horizontal spinning chuck artificially increase the gravitational acceleration. (III) Coating micrometer and nanometer layers which the said horizontal and the said vertical rotations can be performed independently or simultaneously.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 shows an X-direction view of the Two-Axis spin coating device according to an embodiment of the invention with its different parts numbered and marked.

[0040] FIG. 2 shows a perspective view of the Two-Axis spin coating device according to an embodiment of the invention with its different parts numbered and marked.

[0041] FIG. 3 shows a perspective view of the Two-Axis spin coating device according to an embodiment of the invention which shows a schematic representation of the vertical and horizontal rotations of the device.

[0042] FIG. 4 shows a closer perspective view of the horizontal rotation system and parts of the Two-Axis spin coating device according to the embodiment of the invention.

[0043] FIG. 5 shows a schematic effect of elevated artificial gravity acceleration on film's surface leveling using the Two-Axis spin coating method according to the embodiment of the invention.

[0044] FIG. 6 shows a schematic effect of elevated artificial gravity acceleration on film's air bubbling using the Two-Axis spin coating method according to the embodiment of the invention.

[0045] FIG. 7 shows a schematic effect of elevated artificial gravity acceleration on film's edge beading using the Two-Axis spin coating method according to the embodiment of the invention.

[0046] FIG. 8 shows a flow chart process of the Two-Axis spin coating method according to the embodiment of the present invention.

[0047] FIG. 9 shows the manufactured innovated device which is named Two-Axis spin coating apparatus.

[0048] FIG. 10 shows a Cross-Section SEM Image of a photoresist (AZP4620) layer coated by the Two-Axis spin coating method.

[0049] FIG. 11 shows a Cross-Section SEM Image of a photoresist (SU8-3050) layer coated by the conventional spin coating method.

[0050] FIG. 12 shows a Cross-Section SEM Image of a photoresist (SU8-3050) layer coated by the Two-Axis spin coating method.

[0051] FIG. 13 shows a surface SEM Image of a photoresist (SU8-3050) layer coated by the conventional spin coating method.

[0052] FIG. 14 shows a surface SEM Image of a photoresist (SU8-3050) layer coated by the Two-Axis spin coating method.

[0053] FIG. 15 shows a Cross-Section SEM Image of a photoresist (SU8-3050) layer coated by the conventional spin coating method.

[0054] FIG. 16 shows a Cross-Section SEM Image of a photoresist (SU8-3050) layer coated by the Two-Axis spin coating method.

DETAILED DESCRIPTION OF THE INVENTION

[0055] Referring to FIGS. 1, 2, 3, and 4, in accordance with an embodiment of the innovated present apparatus, various sizes and different types of substrates and wafers can settle on a horizontal spinning chuck 7. An electric motor 11 is adjusted on a bracket holder 9 to supply the rotation of the horizontal spinning chuck 7. The rotation power of the motor 11 can be transmitted to the spinning chuck 7 by a belt 6. The belt 6 transmits the rotation of a pulley 5 which is connected to the motor 11 to a pulley 8 which is connected to the spinning chuck 7. The horizontal spinning chuck system 7 is connected to the bracket holder 9 by a bearing and bearing holder 10. The bracket holder 9 is connected to a vertical rotating disk 3.

[0056] The substrates can be sucked to be held on the horizontal spinning chuck 7 by an air vacuum pump 20. The vacuumed air generated by the vacuum pump 20 can be passed through a vacuum pipe 19, a bearing and bearing holder 18, a vacuum air channel through the main shaft 16, a vacuum pipe 4, the bearing and bearing holder 10, and an air channel in the center of the horizontal spinning chuck 7. One head of the vacuum pipe 4 is connected to the bearing holder 10 and the other head is connected to the main shaft 16. There is an air channel along the longitudinal of the main shaft 16 which the generated vacuumed air by the vacuum pump 20 can be passed from the vacuum pipe 19 to the vacuum pipe 4. The bearing and bearing holder 18 connect the vacuum pipe 19 to the main shaft 16. The bearing and bearing holder 18 prevent the rotation of vacuum pipe 19 while the main shaft 16 is rotating.

[0057] The main shaft 16 can be rotated by an electric motor 24. A pulley 23 and a pulley 17 are connected to the electric motor 24 and the main shaft 16 accordingly. The pulley 23 transmits rotation power of the electric motor 24 to the pulley 17 and subsequently to the main shaft 16 by a power transmission belt 22. The main shaft 16 rotates and holds the vertical rotating disk 3 by two bearings and bearing holders 15 and 18. The bearings and bearing holders 15 and 18 let the main shaft 16 be rotated and hold the rotating disk 3 on two pedestals 12 and 25. The pedestals 12 and 25 connect the main shaft 16 and accordingly vertical rotating disk 3 to a base plate 13. The electric motor 24 is adjusted on the pedestal 25. The vacuum pump 20 is also adjusted on the pedestal 25 by a base plate 21.

[0058] To balance the mass rotation of the vertical rotating disk 3, a balancing mass 2 is adjusted on the vertical rotating disk 3 at the reverse side of the horizontal rotating components. The balancing mass 2 is connected to the vertical rotating disk 3 by a bracket holder 1. The mass of balancing mass 2 is evaluated in such a way to be equal to the horizontal rotating components including the electric motor 11, the bearing and the bearing holder 10, the both pulleys 5 and 8, the spinning chuck 7, the power transmission belt 6, and the vacuum pipe 4. This action to balance the mass objects on both sides of the vertical rotating disk 3 will prevent the device from vibrating at high vertical rotation speeds.

[0059] It is not possible to transmit electric power to electric motor 11 through wires simultaneously while the vertical rotating disk 3 is rotating. Therefore, for this electric power transmission, the innovative device needs a rotational power distributer to deliver the electric power to the components such as the electric motor 11 or any other attach equipment or sensors. The required electricity power of the DC electric motor 11 can be transmitted by a rotational power distributor 14. The rotational power distributor 14 can also transmit other probable required electricity power such as the power of sensors or other electric components into the vertical rotating system, and vice versa receive signals from those components and transmit them out while rotating the vertical rotating disk 3.

[0060] The innovative apparatus is designed and manufactured in such a way that the rotation speed of both the horizontal and vertical rotations can be controlled simultaneously. The horizontal rotation acts like the conventional spin coaters to spread the coating over the substrate and the vertical rotation generates the centrifuge acceleration and accordingly generates the artificial gravity acceleration perpendicular to the substrate. This controllable elevated artificial gravity acceleration on the elements of coating is the invention within the mentioned apparatus.