A spin coating defect suppression method based on electric field regulation and liquid return redistribution mechanism

Abstract

The application discloses a kind of based on electric field regulation and liquid redistribution of spin coating defect inhibition method, including the following steps: initialization stage;Liquid spreading stage;Dynamic equilibrium stage and drying and solidification stage.The application first embeds electric wetting control technology in spin coating structure, by arranging the radially distributed annular electrode piece and the multiple rectangular electrode pieces inserted in outer annular electrode piece, inner annular electrode piece and middle annular electrode piece mainly act on the process of liquid film spreading, rectangular electrode piece and outer two annular electrode pieces form many small fan-shaped subareas, control the edge film thickness of corresponding area in spin coating process;By different voltage to electrode piece, realize to apply spatial variable electric field, realize active regulation to liquid wettability.Control mode is non-contact, reversible and high response speed, can complete wetting state switching within millisecond level time.The application solves the imbalance problem of insufficient center liquid and excessive edge liquid.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano manufacturing and optoelectronic thin film preparation technology, specifically relating to a spin coating method and apparatus for high uniformity thin film deposition, and in particular a spin coating defect suppression method that combines dynamic electric field control and liquid redistribution mechanism. Background Technology

[0002] Spin coating is a core process for the preparation of optical thin films, photoresist layers, perovskite films, and polymer films, which are widely used in various applications. It involves rotating a liquid to spread it on a substrate surface, enabling the formation of highly uniform films in a short time. However, when the substrate diameter is large or the material system is complex, the spin coating process is often accompanied by defects such as edge thick peaks, uneven film thickness, and drying ripples.

[0003] Traditional spin coating control methods mainly improve uniformity by adjusting the spin speed, temperature, or solvent evaporation rate. However, these methods are limited in scope and have a slow response, making it particularly difficult to suppress edge liquid buildup in the real-time dynamic process of film thickness evolution. Furthermore, the radial imbalance between insufficient central liquid volume and excessive edge liquid volume caused by edge liquid ejection is especially prominent in large-diameter or high-viscosity material systems.

[0004] The wettability of liquids at interfaces is significantly affected by electric fields. Electrowetting technology can actively control the spreading behavior of liquids by adjusting the contact angle between the liquid and solid interfaces through voltage. Introducing electric field regulation into the spin coating process, combined with a dynamic liquid recovery and redistribution system, will help achieve balanced regulation of the spin-coated liquid film.

[0005] Therefore, there is an urgent need for a multi-physics field coupled spin coating device that integrates electrowetting control and liquid redistribution functions, so as to monitor and control the behavior of the liquid film in real time during the spin coating process, suppress edge defects from the root, and improve the uniformity and repeatability of the film. Summary of the Invention

[0006] The purpose of this invention is to provide a spin coating defect suppression method based on electric field modulation and liquid redistribution mechanism. By controlling the liquid wettability and liquid recovery and redistribution in the spin coating process, the method can achieve efficient suppression of microstructure edge defects and improve film thickness uniformity.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: a spin coating defect suppression method based on electric field control and liquid return redistribution, which utilizes a spin coating defect suppression device based on electric field control and liquid return redistribution to suppress spin coating defects. The spin coating defect suppression device based on electric field control and liquid return redistribution includes, from top to bottom, a nozzle, a substrate, an insulating layer, a base layer, a rotating shaft, a base platform, and a liquid return pipe. The nozzle is located above the substrate and is connected to the upper end of the return liquid pipe. The substrate is fixed on the insulating layer by vacuum adsorption. The insulating layer is disc-shaped and equipped with a vacuum suction cup. The insulating layer has pores along its circumference and an annular return groove. Multiple internal micro-conduits A are provided, connecting to the bottom surface of the insulating layer and communicating with all pores and the bottom of the return groove. Each internal micro-conduit A connected to a pore has an individual on / off function to control the operation of the pore. The lower surface of the insulating layer is connected to the upper surface of the base layer. The base layer is disc-shaped, with three concentric annular electrode slots radially distributed inside: an inner annular electrode slot, a middle annular electrode slot, and an outer annular electrode slot. Multiple rectangular electrode slots perpendicular to the top surface of the base layer are formed between the middle and outer annular electrode slots. Inner annular electrodes, middle annular electrodes, outer annular electrodes, and rectangular electrodes are embedded within the inner, middle, and outer annular electrode slots and rectangular electrode slots, respectively, forming different electric field control regions. The base layer has the same number of internal microducts B as microduct A, which are concentric, vertically aligned, and connected to the internal microduct A. The internal microducts B converge into a single channel within the base layer. The base layer is fixed to the base platform via a rotating shaft. The rotating shaft has an internal microcatheter C; The base has an internal microcatheter D; The upper end of the return pipe is connected to a nozzle, and the lower end is connected to the internal microcatheter D of the base. The return liquid circuit starts from microcatheter A, passes through internal microcatheter B, and then passes through internal microcatheter B again to converge into a main conduit inside the base layer, internal microcatheter C, internal microcatheter D, and finally returns to the nozzle through the return liquid pipe, which constitutes the return liquid circuit; when one or more vents need to work, the internal microcatheter A of the corresponding vent opens, and the air pressure in the entire return liquid circuit is controlled by the air pump, and the corresponding vent draws in liquid through the air pressure difference; The nozzle vertically sprays liquid onto the substrate surface; The spin coating defect suppression method includes the following steps: A. Initialization Phase: The initial voltage distribution of the substrate electrode plates is set, and the liquid on the substrate initially spreads under low-speed rotation. The return liquid circuit air pump is shut off and does not actively absorb liquid.

[0008] B. Liquid Spreading Stage: As the rotational speed increases, the liquid spreads outward from the center. Adjusting the voltage of the edge electrodes gradually applies a weak electric field to the space, regulating the liquid contact angle, promoting rapid liquid spread, eliminating initial bubbles or uneven layers, and suppressing early edge accumulation.

[0009] C. Dynamic Equilibrium Stage: By controlling the voltage applied to the electrode plates, the electric field strength in a region is changed, altering the liquid contact angle and generating an inward pull force to suppress the formation of thick peaks. Simultaneously, the return liquid circuit air pump is activated to draw in some of the edge liquid, and the recovered liquid is then sprayed back into the central area through nozzles, achieving liquid reflux and redistribution.

[0010] D. Drying and Curing Stage: As the liquid thins, the voltage on the electrode plates is gradually reduced to change the electric field strength and prevent the formation of a drying ring. This ultimately results in a film layer with uniform thickness and smooth edges.

[0011] Furthermore, the number of pores in the insulating layer and the number of pores in each pore are determined according to requirements.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention is the first to embed electrowetting control technology into a spin-coating structure. It utilizes radially distributed annular electrode sheets and multiple rectangular electrode sheets inserted within the outer annular electrode sheets. The inner and middle annular electrode sheets primarily function during the liquid film spreading process. The rectangular electrode sheets and the two outer annular electrode sheets form numerous small fan-shaped zones, controlling the edge film thickness of corresponding areas during spin-coating. By applying different voltages to the electrode sheets, a spatially variable electric field is applied, enabling active adjustment of the liquid's wettability. The control method is non-contact, reversible, and has a high response speed, completing wetting state switching within milliseconds.

[0013] 2. This invention proposes a closed-loop liquid circulation system consisting of edge return liquid—center re-spray—radial redistribution. When the edge liquid thickness is too large, the vent and return liquid tank draw in excess liquid through the air pressure applied by the air pump. The drawn-in liquid is then re-sprayed onto the liquid film surface through the nozzle via the return liquid circuit, forming a radial redistribution flow. This solves the imbalance problem of insufficient liquid volume in the center and excessive liquid volume at the edge, significantly improving film thickness uniformity and material utilization. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention.

[0015] Figure 2 This is a schematic diagram (exploded view) of the structure of the present invention.

[0016] Figure 3 This is a schematic diagram of the connection between the insulating layer and the base layer of the present invention.

[0017] Figure 4 This is a schematic diagram of the insulating layer structure of the present invention.

[0018] Figure 5 This is a schematic diagram of the base structure of the present invention.

[0019] Figure 6This is a schematic diagram of the electrode sheet structure of the present invention.

[0020] In the diagram: 1-Return liquid pipe; 2-Nozzle; 3-Substrate; 4-Insulating layer; 5-Base layer; 6-Rotating shaft; 7-Base platform; 8-Electrode plate; 9-Pore; 10-Return liquid tank; 11-Internal microcatheter A; 12-Vacuum chuck; 13-Inner annular electrode plate groove; 14-Middle annular electrode plate groove; 15-Outer annular electrode plate groove; 16-Rectangular electrode plate groove; 17-Internal microcatheter B; 18-Inner annular electrode plate; 19-Middle annular electrode plate; 20-Outer annular electrode plate; 21-Rectangular electrode plate. Detailed Implementation

[0021] The present invention will now be further described with reference to the accompanying drawings.

[0022] like Figure 1-6 As shown, a spin coating defect suppression method based on electric field control and liquid return redistribution is used to suppress spin coating defects. The spin coating defect suppression device based on electric field control and liquid return redistribution includes, from top to bottom, a nozzle 2, a substrate 3, an insulating layer 4, a base layer 5, a rotating shaft 6, a base 7, and a liquid return pipe 1. The nozzle 2 is located above the substrate 3 and is connected to the upper end of the return pipe 1. The substrate 3 is fixed on the insulating layer 4 by vacuum adsorption. The insulating layer 4 is disc-shaped and is equipped with a vacuum suction cup 12. The insulating layer 4 has pores 9 along its circumference and an annular return groove 10. The insulating layer 4 is provided with multiple internal micro-conduits A11, which connect to the bottom surface of the insulating layer 4 and are connected to all pores 9 and the bottom of the return groove 10. Each internal micro-conduit A11 connected to a pore 9 has an individual opening or closing function to control whether the pore 9 is working or not. The lower surface of the insulating layer 4 is connected to the upper surface of the base layer 5. The base layer 5 is disc-shaped. Three concentric annular electrode slots are radially arranged inside the base layer 5: an inner annular electrode slot 13, a middle annular electrode slot 14, and an outer annular electrode slot 15. Multiple rectangular electrode slots 16 perpendicular to the top surface of the base layer are formed between the middle annular electrode slot 14 and the outer annular electrode slot 15. Inner annular electrode plates 18, middle annular electrode plates 19, outer annular electrode plates 20, and rectangular electrode plates 21 are embedded in the inner annular electrode slot 13, middle annular electrode slot 14, outer annular electrode slot 15, and rectangular electrode slots 16, respectively, forming different zones of electric field control areas. The base layer 5 has the same number of internal micro-conduits B17 as the micro-conduit A. The internal micro-conduits B17 have the same radius as the internal micro-conduits A11 and are concentric, vertically aligned, and connected. The internal micro-conduits B17 converge into a single channel within the base layer 5. The base layer 5 is fixed to the base platform 7 via a rotating shaft 6. The upper end of the return pipe 1 is connected to the nozzle 2, and the lower end is connected to the internal microcatheter D of the base 7.

[0023] The spin coating defect suppression method includes the following steps: A. Initialization Phase: The initial voltage distribution of the base layer 5 electrode sheet 8 is set, and the liquid on the substrate 3 initially spreads under low-speed rotation. The return liquid circuit air pump is shut off, and no liquid is actively absorbed. The electrode sheet 8 includes an inner annular electrode sheet 18, a middle annular electrode sheet 19, an outer annular electrode sheet 20, and a rectangular electrode sheet 21.

[0024] B. Liquid Spreading Stage: As the rotational speed increases, the liquid spreads outward from the center. Adjusting the voltage of the edge electrode plate 8 gradually applies a weak electric field to the space, adjusting the liquid contact angle, promoting rapid liquid spread and eliminating initial bubbles or uneven layers, and suppressing early edge accumulation.

[0025] C. Dynamic Equilibrium Stage: By controlling the voltage applied to electrode 8, the electric field strength in a region is changed, altering the liquid contact angle and generating an inward pull force to suppress the formation of thick peaks. Simultaneously, the air pump on the return liquid circuit is activated to draw in some of the edge liquid, and the recovered liquid is then sprayed back into the central region of substrate 3 through nozzle 2, achieving liquid reflux and redistribution.

[0026] D. Drying and Curing Stage: As the liquid thins, the voltage of electrode plate 8 is gradually reduced to change the electric field strength and prevent the formation of a drying ring. This ultimately results in a film layer with uniform thickness and smooth edges.

[0027] Furthermore, the number of turns of air holes 9 on the insulating layer 4 and the number of air holes 9 per turn are determined according to requirements.

[0028] Furthermore, the rotating shaft 6 has an internal microcatheter C; the base 7 has an internal microcatheter D; The return liquid circuit starts from microcatheter A, passes through internal microcatheter B17, and then passes through internal microcatheter B17 to converge into a main conduit inside the base layer 5, internal microcatheter C, internal microcatheter D, and finally returns to nozzle 2 through return liquid pipe 1, which constitutes the return liquid circuit; when one or more vents 9 need to work, the internal microcatheter A11 of the corresponding vent 9 opens, and the air pressure in the entire return liquid circuit is controlled by the air pump, and the corresponding vent 9 draws in liquid through the air pressure difference; The nozzle 2 sprays liquid vertically onto the surface of the substrate 3.

[0029] As described above, those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts of this invention, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A method for suppressing spin-coating defects based on electric field modulation and liquid redistribution, characterized in that: Spin coating defect suppression is performed using a spin coating defect suppression device based on electric field control and liquid return redistribution. The spin coating defect suppression device based on electric field control and liquid return redistribution includes, from top to bottom, a nozzle (2), a substrate (3), an insulating layer (4), a base layer (5), a rotating shaft (6), a base plate (7), and a liquid return pipe (1). The nozzle (2) is located above the substrate (3) and connected to the upper end of the return pipe (1). The substrate (3) is fixed on the insulating layer (4) by vacuum adsorption. The insulating layer (4) is disc-shaped and is provided with a vacuum suction cup (12); the insulating layer (4) is provided with pores (9) along its circumference and has an annular return groove (10); the insulating layer (4) is provided with multiple internal micro-conduits A (11), which are connected to the bottom surface of the insulating layer (4) and are connected to the bottom of all pores (9) and the return groove (10); each internal micro-conduit A (11) connected to the pore (9) has an individual opening or closing function to control whether the pore (9) is working or not; the lower surface of the insulating layer (4) is connected to the upper surface of the base layer (5); The base layer (5) is disc-shaped, and three concentric annular electrode slots are radially arranged inside the base layer (5), namely an inner annular electrode slot (13), a middle annular electrode slot (14), and an outer annular electrode slot (15); multiple rectangular electrode slots (16) perpendicular to the top surface of the base layer are formed between the middle annular electrode slot (14) and the outer annular electrode slot (15); the inner annular electrode slot (13), the middle annular electrode slot (14), the outer annular electrode slot (15), and the rectangular electrode slots (16) The inner ring electrode sheet (18), middle ring electrode sheet (19), outer ring electrode sheet (20) and rectangular electrode sheet (21) are embedded in the base layer (5) to form electric field control areas in different zones; the base layer (5) has the same number of internal microcatheters B (17) as the microcatheter A, the internal microcatheters B (17) and the internal microcatheter A (11) have the same radius and are concentric and vertically aligned and connected; the internal microcatheters B (17) are gathered into a channel inside the base layer (5); the base layer (5) is fixed on the base plate (7) by a rotating shaft (6); The upper end of the return pipe (1) is connected to the nozzle (2), and the lower end is connected to the internal micro-conduit D of the base (7); The spin coating defect suppression method includes the following steps: A. Initialization stage: Set the voltage distribution of the initial electrode sheet (8) of the base layer (5), and the liquid on the substrate (3) forms the initial spread of the liquid under low speed rotation; the return liquid circuit air pump is closed and does not actively absorb the liquid; the electrode sheet (8) includes an inner ring electrode sheet (18), a middle ring electrode sheet (19), an outer ring electrode sheet (20) and a rectangular electrode sheet (21). B. Liquid spreading stage: When the rotation speed increases, the liquid spreads from the center outward; adjust the voltage of the edge electrode (8) to gradually apply a weak electric field to the space, adjust the liquid contact angle, promote the rapid spreading of the liquid and eliminate the initial bubbles or uneven layer, and suppress early edge accumulation; C. Dynamic Equilibrium Stage: By controlling the voltage applied by the electrode sheet (8), the electric field strength of a region is changed, the liquid contact angle is changed, and an inward pull force is generated to suppress the formation of thick peaks; at the same time, the air pump on the return liquid circuit is turned on to draw out part of the edge liquid, and the recovered liquid is sprayed back to the center area of ​​the substrate (3) through the nozzle (2) to realize the return and redistribution of liquid; D. Drying and curing stage: As the liquid thins, the voltage of the electrode sheet (8) is gradually reduced to change the electric field strength and prevent the formation of a drying ring; finally, a film layer with uniform thickness and smooth edges is formed.

2. The spin coating defect suppression method based on electric field modulation and liquid redistribution according to claim 1, characterized in that: The number of turns of the air holes (9) on the insulating layer (4) and the number of air holes (9) per turn are determined according to the requirements.

3. The spin-coating defect suppression method based on electric field modulation and liquid redistribution according to claim 1, characterized in that: The rotating shaft (6) has an internal micro-conduit C; the base (7) has an internal micro-conduit D; the return circuit starts from micro-conduit A, passes through internal micro-conduit B (17), and then passes through internal micro-conduit B (17) to converge into a main conduit, internal micro-conduit C, and internal micro-conduit D in the base layer (5), and finally returns to the nozzle (2) through the return pipe (1), which constitutes the return circuit; when one or more vents (9) need to work, the internal micro-conduit A (11) of the corresponding vent (9) is opened, and the air pressure in the entire return circuit is controlled by the air pump, and the corresponding vent (9) draws in liquid through the air pressure difference; The nozzle (2) sprays liquid vertically onto the surface of the substrate (3).

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