Splash-back prevention base of photoresist spin coater
By improving the base structure of the photoresist spin coater and using inclined side walls, multi-step steps and spoiler ring design, the problem of photoresist rebound and splashing was solved, achieving a more uniform spin coating effect and higher yield.
Patent Information
- Application Number
- CN202510860026.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-25
- Publication Date
- 2025-09-26
AI Technical Summary
The base structure of existing photoresist spin coaters causes the photoresist to easily bounce back and splash onto the substrate surface during high-speed rotation, resulting in uneven film and particle contamination defects.
A splash-back prevention base was designed, which includes side walls with inclined inner surfaces and multiple steps, combined with guide grooves and spoiler rings. The changes in the inclination angle and airflow direction are used to reduce the rebound of photoresist droplets, discharge the splashing droplets through the exhaust holes, and coat the surface with a hydrophobic and oleophobic fluorinated silicon coating to prevent adhesion.
It effectively reduces the rebound and splashing of photoresist droplets, improves the uniformity of spin coating, reduces the defect rate, and improves the yield rate.
Smart Images
Figure CN120696041A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of photoresist spin coating, in particular to an anti-splashing base of a photoresist spin coating machine. Background Art
[0002] Substrates are widely used in fields such as semiconductor manufacturing and micro-nanofabrication. Spin coating photoresist on substrates is a key step in the photolithography process. Its purpose is to form a uniform, thin, and precise photoresist coating on the substrate surface, laying the foundation for subsequent pattern transfer (such as exposure and development). The spin coating process involves dropping photoresist onto the center of the substrate. High-speed rotation causes the glue to diffuse toward the edges under centrifugal force while the solvent evaporates, ultimately forming a film of uniform thickness. The flow state of the glue during the spin coating process determines whether defects such as bubbles and particles will form, and whether a smooth, dense surface can be achieved.
[0003] See also Figure 1 , which is a base structure diagram of an existing traditional photoresist spin coater. The base is a cylindrical straight-wall structure. After the substrate is spin-coated, the photoresist film on the substrate occasionally has defects such as unevenness and particle contamination. Summary of the Invention
[0004] Based on this, the purpose of the present invention is to overcome the defects or shortcomings of the prior art and provide an anti-splashing base for a photoresist spin coater.
[0005] A backsplash prevention base for a photoresist spin coater comprises a base plate and a side wall. The base plate and the side wall are fixedly connected to form a cylinder with a one-way opening. The inner surface of the side wall is inclined toward the inside of the base and forms an inclination angle with the base plate that is less than 90 degrees.
[0006] Furthermore, the inner surface of the sidewall is provided with multiple steps, wherein the inner surface of each step facing the interior of the base is inclined inwardly of the base and forms an angle with the bottom plate that is less than 90 degrees. By providing multiple steps, each step has a corresponding inclination angle, thereby preventing the steps from encroaching excessive space inside the base and optimizing the spatial structure design.
[0007] Furthermore, the included angle between the inclination angle and the vertical direction is between 15° and 45° to achieve a better anti-splashback effect.
[0008] Since the inner surface of the side wall or step has an inward inclination angle, for the photoresist droplets whose angle between the throwing direction and the horizontal plane is smaller than the angle between the normal direction of the inner surface of the side wall or step and the horizontal plane, the direction in which the photoresist droplets are rebounded by the side wall forms an acute angle with the vertical plane. Therefore, it will be difficult for these bounced photoresist droplets to be bounced back onto the substrate.
[0009] Furthermore, a guide groove is provided on the side wall, which extends from the top of the side wall through the multi-level steps and connects to the bottom plate. The width of the guide groove is 3-5 mm, so as to prevent photoresist droplets from accumulating on the inner surface of the side wall or the steps, causing secondary rebound and splashing.
[0010] Furthermore, the number of the steps is 3-5, and the height of the steps is 12-15 mm.
[0011] Furthermore, an annular spoiler ring is provided at the top of the side wall, and guide teeth are provided on the lower surface of the spoiler ring facing the base plate. A spiral downward vortex is formed at the bottom of the spoiler ring, which exerts a force directed toward the base plate on splashing photoresist droplets, making it difficult for the photoresist droplets to rebound upward, reducing the rebound distance of the photoresist droplets, and making them less likely to be splashed onto the substrate.
[0012] Furthermore, the inner ring diameter of the spoiler ring is larger than the diameter of the substrate to be coated with glue, so that the substrate can be smoothly placed in the base.
[0013] Furthermore, the guide teeth are sawtooth-shaped with a tooth height of 1-3 mm and a tooth spacing of 0.5-1 mm, thereby further increasing the downward flow velocity of the radial centrifugal airflow and enhancing the force exerted by the spiral downward vortex on the splashing photoresist droplets directed toward the base plate.
[0014] Furthermore, an exhaust hole is provided at the bottom of the side wall, and when the photoresist spin coater is working, air is drawn into the base through the exhaust hole to discharge the splashed photoresist accumulated at the bottom of the base plate.
[0015] Furthermore, the surfaces of the base plate, sidewalls, steps, and spoiler ring are all provided with a hydrophobic and oleophobic silicon fluoride coating. This prevents photoresist droplets from adhering to the surfaces of the base plate, sidewalls, steps, and spoiler ring upon contact, thereby preventing photoresist droplets from accumulating on the surfaces and causing secondary splash pollution.
[0016] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a schematic diagram of the base structure of an existing photoresist spin coater;
[0018] Figure 2 Schematic diagram of the anti-splashing base structure of the photoresist spin coater of the present invention;
[0019] Figure 3 A cross-sectional view of an anti-splashing base of a photoresist spin coater according to the present invention;
[0020] Figure 4 It is a structural schematic diagram of the multi-step ladder and guide groove of the present invention;
[0021] Figure 5 Schematic diagram of the spoiler ring structure of the present invention. DETAILED DESCRIPTION
[0022] In order to solve the problem that the existing traditional photoresist spin coater is prone to uneven film thickness and film defects during spin coating. The inventor has analyzed why the existing photoresist spin coater has the problem of uneven coating. The inventor found that because the base of the existing photoresist spin coater is a cylindrical structure, during the high-speed rotation process, after the photoresist is thrown out due to centrifugal force, part of the photoresist will rebound and splash onto the substrate surface, eventually forming the defects of uneven film and particle contamination. On the other hand, when the photoresist spin coater is working, the high-speed rotation of the base and substrate will generate a strong horizontal outward radial centrifugal airflow, which increases the speed at which the splashed photoresist droplets hit the side walls of the base, causing the rebounded photoresist droplets to have a higher speed and be more likely to be rebounded back to the substrate surface, thereby forming the defects of uneven film and particle contamination.
[0023] Based on this, the present invention designs a back-splash prevention base for a photoresist spin coater. By improving the base structure of the photoresist spin coater, the invention prevents the photoresist thrown out by centrifugal force during high-speed rotation from rebounding back to the substrate surface after contacting the sidewall of the base or being carried back to the substrate surface by airflow.
[0024] See also Figure 2 , which is a structural diagram of an anti-splashing base of a photoresist spin coater of the present invention. The base 10 includes a bottom plate 12 and a side wall 14, and the bottom plate 12 and the side wall 14 are fixedly connected to form a cylinder with a one-way opening.
[0025] The bottom of the side wall 14 has a plurality of exhaust holes 142, which are evenly distributed. When the base 10 rotates, the photoresist spin coater evacuates air from the interior of the base 10 through the exhaust holes 142. At the same time, when the photoresist splashed from the substrate flows onto the bottom plate 12, it is discharged through the exhaust holes 142, thereby preventing the accumulation of photoresist on the bottom plate 12. The inner surface of the side wall 14 is inclined toward the interior of the base 10 and forms an angle with the bottom plate 12 that is less than 90°. Preferably, the angle between the inclination angle and the vertical direction is between 15° and 45°. When the substrate is mounted and fixed at the center of the base 10 and rotates at high speed with the base 10, the photoresist on the substrate is thrown out to form photoresist droplets and emitted onto the side wall 14 of the base 10. Since the inner surface of the side wall 14 has an inward tilt angle, at this time, for the photoresist droplets whose angle between the throwing direction and the horizontal plane is smaller than the angle between the normal direction of the inner surface of the side wall 14 and the horizontal plane, the direction in which the photoresist droplets are rebounded by the side wall 14 forms an acute angle with the vertical plane. Therefore, it is difficult for these partially rebounded photoresist droplets to be rebounded back onto the substrate.
[0026] Preferably, see Figure 3 The inner surface of the sidewall 14 is provided with multiple steps 144. Each step 144, facing the interior of the base 10, is inclined toward the interior of the base 10 and forms an angle with the bottom plate 12 that is less than 90°. The angle between the vertical direction and the angle is between 15° and 45°. If there were only a single inclined surface, the inner surface of the sidewall 14 would encroach excessively into the interior of the base 10 due to the inclination. By providing multiple steps 144, each step 144 has a corresponding inclination angle, preventing excessive encroachment into the interior of the base 10, thereby optimizing the spatial structure design.
[0027] See also Figure 4 The side wall 14 is also provided with a guide groove 145, which runs from the top of the side wall through the multiple steps and is connected to the bottom plate. When the photoresist droplets are emitted onto the inner surface of the step 144, the droplets will flow downward along the guide groove 145 to the next step or the bottom of the base 10, and then be discharged through the exhaust hole 142 to avoid the photoresist droplets accumulating on the inner surface of the side wall 14 or the step 144, causing secondary rebound and splashing.
[0028] Preferably, the number of the steps 144 is 3-5, the height of the steps 144 is 12-15 mm, and the width of the guide groove 145 provided between two adjacent steps 144 is 3-5 mm.
[0029] Further, see Figure 5 To prevent some photoresist droplets from being carried back to the substrate surface by the chaotic airflow and causing contamination, an annular spoiler ring 146 is provided on the top of the sidewall 14. The spoiler ring has a height of 1-2 mm and extends 3-5 mm into the interior of the base 10. The inner diameter of the spoiler ring is larger than the diameter of the substrate to be coated. When the substrate to be coated is placed in the base 10, a gap of 0.5-1 mm is reserved between its edge and the spoiler ring 146, so that the substrate can be smoothly placed in the base 10. A plurality of guide teeth 1462 are provided on the lower surface of the spoiler ring 146, which faces the bottom plate 12 of the base 10. When the base 10 rotates at high speed for glue spreading, the guide teeth 1462 on the spoiler ring 146 can change the direction of the airflow inside the base 10 and form a downward vortex, so that the splashing photoresist droplets are subjected to a downward force by the airflow, guiding the photoresist droplets downward to the bottom of the base 10 and discharging the photoresist droplets from the exhaust hole 142.
[0030] Specifically, when the spoiler ring 146 is not set, when the photoresist spin coater rotates at high speed, the gas attached to the surface of the substrate, the bottom plate 12, and the side wall 14 rotates together under the action of viscous force, so that a complex airflow movement is formed inside the base 10. The gas is subjected to an outward centrifugal force, thereby forming a strong radial centrifugal airflow. This airflow increases the force of the photoresist droplets splashed from the substrate to be emitted onto the side wall 14 or the step 144, so that the photoresist droplets are sputtered farther when they are rebounded, and are more likely to be sputtered onto the substrate, forming defects such as uneven coating.
[0031] When the spoiler ring 146 is provided, the radial centrifugal airflow formed during high-speed rotation of the photoresist spin coater is blocked by the spoiler ring 146 when it hits the spoiler ring 146. Furthermore, due to the presence of the spoiler teeth 1462, the originally horizontally outward radial centrifugal airflow is redirected by the guide teeth 1462 to form a downward-flowing airflow. Simultaneously, the guide teeth 1462 also generate a vertically downward-flowing airflow during high-speed rotation. The simultaneous action of these two airflows forms a spiral downward vortex at the bottom of the spoiler ring 146. This vortex exerts a force directed toward the base plate 12 on the splashing photoresist droplets, making it difficult for the photoresist droplets to rebound upward, reducing the distance they can bounce back and making them less likely to be sputtered onto the substrate and less likely to form defects.
[0032] Preferably, the guide teeth 1462 are serrated, with a tooth height of 1-3 mm and a tooth spacing of 0.5-1 mm. Due to the serrated structural design, when the horizontally outward radial centrifugal airflow strikes the guide teeth 1462, the airflow velocity at the tooth tips is greater than the airflow velocity at the tooth roots. According to Bernoulli's theorem, the airflow pressure at the tooth tips is less than the airflow pressure at the tooth roots. This further increases the downward flow velocity of the radial centrifugal airflow and enhances the force exerted by the spiral downward vortex on the splashing photoresist droplets directed toward the base plate 12.
[0033] Preferably, the surfaces of the bottom plate 12, side wall 14, step 144 and spoiler ring 146 are all provided with a hydrophobic and oleophobic silicon fluoride coating, so that their surface energy is lower than 30mN / m, so that the photoresist droplets are not easy to adhere to the surface when they contact the surface of the bottom plate 12, side wall 14, step 144 and spoiler ring 146, thereby preventing the photoresist droplets from accumulating on their surface and causing secondary splash pollution.
[0034] Compared to existing photoresist spin coaters, the anti-splash base of the present invention's photoresist spin coater, by improving its sidewall structure, prevents photoresist ejected by centrifugal force during high-speed rotation from rebounding back onto the substrate surface after contacting the base's sidewalls or being repelled by airflow. This improves the uniformity of the substrate's spin coating process in the photoresist spin coater, reduces the risk of defects, and increases product yield.
[0035] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, and the present invention is intended to encompass such modifications and variations.
Claims
1. A backsplash prevention base for a photoresist spin coater, characterized in that: The bottom plate and the side wall are fixedly connected to form a cylinder with a one-way opening. The inner surface of the side wall is inclined toward the inside of the base and forms an inclination angle with the bottom plate that is less than 90 degrees.
2. The backsplash prevention base of the photoresist spin coater according to claim 1, characterized in that: The inner surface of the side wall is provided with a plurality of steps, wherein the inner surface of each step facing the inside of the base is inclined toward the inside of the base and forms an inclination angle with the bottom plate that is less than 90°.
3. The backsplash prevention base of the photoresist spin coater according to claim 2, characterized in that: The angle between the inclination angle and the vertical direction is between 15° and 45°.
4. The backsplash prevention base of the photoresist spin coater according to claim 2, characterized in that: The side wall is also provided with a guide groove, which extends from the top of the side wall through the multi-level steps and is connected to the bottom plate. The width of the guide groove is 3-5 mm.
5. The backsplash prevention base of the photoresist spin coater according to claim 4, characterized in that: The number of the steps is 3-5, and the height of the steps is 12-15 mm.
6. The backsplash prevention base of the photoresist spin coater according to claim 2, characterized in that: An annular spoiler ring is provided on the top of the side wall, and flow guide teeth are provided on the lower surface of the spoiler ring facing the bottom plate.
7. The backsplash prevention base of the photoresist spin coater according to claim 6, characterized in that: The inner ring diameter of the spoiler ring is larger than the diameter of the substrate to be coated with glue.
8. The backsplash prevention base of the photoresist spin coater according to claim 6, characterized in that: The guide teeth are sawtooth-shaped, with a tooth height of 1-3 mm and a tooth spacing of 0.5-1 mm.
9. The backsplash prevention base of the photoresist spin coater according to claim 6, characterized in that: The bottom of the side wall is provided with an exhaust hole, and when the photoresist spin coater is working, air is extracted into the interior of the base through the exhaust hole.
10. The backsplash prevention base of the photoresist spin coater according to any one of claims 6 to 9, characterized in that: The surfaces of the bottom plate, side walls, steps and spoiler ring are all provided with a hydrophobic and oleophobic silicon fluoride coating.