Vacuum drying apparatus

Abstract

The present disclosure relates to a vacuum drying apparatus for removing solvent in photoresist. The vacuum drying apparatus of the present disclosure comprises: a vacuum chamber; a flow pipe communicating with the vacuum chamber; a ball valve rotatably arranged in the flow pipe, the ball valve being provided with an exhaust passage, the cross section of the exhaust passage being in the shape of a sector; a driving device in driving connection with the ball valve for driving the ball valve to rotate to adjust the opening degree of the ball valve, the opening degree being the ratio of the overlapping conductive area of the exhaust passage and the flow pipe to the cross section of the exhaust passage.

Description

Technical Field

[0001] This disclosure relates to the field of display technology, and more specifically to a vacuum drying device. Background Technology

[0002] Some film patterns in display panels can be formed using photolithography. Specifically, the process for forming film patterns includes: first, coating a substrate with photoresist; then, vacuum drying the photoresist on the substrate to remove the solvent; and finally, after pre-baking, exposure, and development, forming the desired pattern on the substrate. Vacuum drying is a crucial intermediate step in the photolithography process, used to remove the solvent from the photoresist. The effectiveness of solvent removal directly affects the properties of the photoresist and the subsequent exposure and development processes. Summary of the Invention

[0003] This disclosure aims to solve at least one of the technical problems existing in the prior art, and proposes a vacuum drying device.

[0004] To achieve the above objectives, this disclosure provides a vacuum drying apparatus for removing solvents from photoresist, the vacuum drying apparatus comprising:

[0005] Vacuum chamber;

[0006] A flow channel is connected to the vacuum chamber;

[0007] A ball valve is rotatably disposed within the flow pipe, and the ball valve has an exhaust passage with a fan-shaped cross-section.

[0008] A driving device, connected to the ball valve, is used to drive the ball valve to rotate in order to adjust the opening degree of the ball valve, wherein the opening degree is the ratio of the overlapping conductive area of ​​the exhaust channel and the flow pipe to the cross-section of the exhaust channel.

[0009] In some embodiments, the change in the opening degree of the ball valve is linearly proportional to the change in the theoretical gas flow rate in the flow channel.

[0010] In some embodiments, the vacuum drying equipment further includes a control module configured to control the driving device to rotate the ball valve to adjust the opening degree of the ball valve during the removal of photoresist solvent, and using the following multiple basic opening degrees as control references:

[0011] During the initial pressure reduction phase, the opening degree of the ball valve is controlled to be in the range of 5% to 15%.

[0012] During the rapid pressure reduction phase, the opening degree of the ball valve is controlled to be in the range of 30% to 60%.

[0013] During the pressure reduction and holding phase, the opening degree of the ball valve is controlled to be in the range of 10% to 25%.

[0014] During the final pressure reduction stage, the opening degree of the ball valve is controlled to be between 80% and 100%.

[0015] In some embodiments, the vacuum drying equipment further includes a vacuum pumping device, which is connected to the vacuum chamber and configured to sequentially perform the initial decompression stage, the rapid decompression stage, the decompression holding stage, and the final decompression stage, and to pump air according to the following parameters:

[0016] During the initial decompression phase, the goal is to reduce the air pressure in the vacuum chamber from atmospheric pressure to 900-1200 Pa within 15-25 seconds.

[0017] During the rapid decompression phase, the goal is to reduce the gas pressure in the vacuum chamber from 900-1200 Pa to 250-300 Pa within 6-10 seconds.

[0018] During the pressure reduction and holding phase, the goal is to maintain the gas pressure in the vacuum chamber at 250~300Pa for 12~18s.

[0019] During the final decompression stage, the goal is to reduce the air pressure in the vacuum chamber from 250-300 Pa to 20-30 Pa within 4-15 seconds.

[0020] In some embodiments, the control module includes a PID controller configured to acquire the actual air pressure of the vacuum chamber in real time, obtain the deviation value between the actual air pressure of the vacuum chamber and a preset standard pressure curve, and dynamically adjust the PID parameters according to the deviation value to adjust the opening of the ball valve and / or control the vacuuming device through the drive device, so that the deviation value is stabilized within a preset threshold error range. The PID parameters include at least one of a proportional gain parameter P, an integral gain parameter I, and a derivative gain parameter D.

[0021] In some embodiments, during the initial decompression phase, the PID controller employs a high integral gain parameter I that adapts to the linear buck convergence criterion.

[0022] During the rapid decompression phase, the PID controller employs a high proportional gain parameter P that meets the dynamic tracking requirements and a differential gain parameter D that meets the preset damping requirements.

[0023] During the pressure reduction and holding phase, the PID controller employs a low proportional gain parameter P and a high integral gain parameter I to maintain the chamber pressure in dynamic equilibrium.

[0024] During the final decompression stage, the PID controller uses a low proportional gain parameter P and a dynamically fine-tuned integral gain parameter I to make the air pressure in the vacuum chamber converge and stabilize at 20~30Pa.

[0025] In some embodiments, the exhaust passage includes a through hole penetrating the ball valve, the through hole being surrounded by two side walls and an arcuate surface connecting the two side walls;

[0026] And / or, the exhaust passage includes a V-shaped cut, which is enclosed by two side walls.

[0027] In some embodiments, the geometric center of the ball valve is located in the internal region of the exhaust passage.

[0028] In some embodiments, the drive device is configured to drive the ball valve to rotate in a first plane about a first axis as the rotation axis, the first axis being perpendicular to the extension direction of the flow pipe and perpendicular to the extension direction of the exhaust passage, and the first plane being parallel to the extension direction of the flow pipe and parallel to the extension direction of the exhaust passage.

[0029] Wherein, the cross-section of the flow pipe is elliptical, and the ball valve is an ellipsoid;

[0030] Alternatively, the cross-section of the flow channel is circular, and the ball valve is a ball.

[0031] In some embodiments, the central angle of the sector is 30°~120°;

[0032] And / or, the ratio of the cross-sectional area of ​​the exhaust channel to the cross-sectional area of ​​the flow pipe is 30% to 60%. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 This is a process flow diagram of vacuum decompression drying in some embodiments of this disclosure.

[0035] Figure 2A This is a schematic diagram of the butterfly valve in the closed state in some embodiments.

[0036] Figure 2B This is a schematic diagram of the butterfly valve in the open state in some embodiments.

[0037] Figure 3 This is a schematic diagram of the structural composition of a vacuum drying apparatus in some embodiments of this disclosure.

[0038] Figure 4A and Figure 4B This is a schematic diagram of the structure of a ball valve in some embodiments of this disclosure.

[0039] Figure 5 This is a schematic diagram of the ball valve in some other embodiments of this disclosure.

[0040] Figure 6 These are simulation effect diagrams of some embodiments of this disclosure.

[0041] Figure 7 This is a schematic diagram of the connection relationship of the PID controller in some embodiments of this disclosure.

[0042] Figure 8 This is a comparison chart of time-pressure curves in some embodiments of this disclosure. Detailed Implementation

[0043] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0045] Unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0046] As used herein, “parallel” and “perpendicular” include the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable range of deviation for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable range of deviation for approximate perpendicularity may also be, for example, within 5°.

[0047] This document describes exemplary embodiments with reference to sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and regions is enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Therefore, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. Thus, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0048] In the process of manufacturing display panels, it is necessary to pattern the film layers.

[0049] For example, an Organic Light Emitting Diode (OLED) display panel includes a substrate, a driving circuit layer located on one side of the substrate, and a light-emitting device layer located on the side of the driving circuit layer away from the substrate. The driving circuit layer includes multiple driving circuits, and the light-emitting device layer includes multiple light-emitting devices. The driving circuits are electrically connected to the light-emitting devices, and the driving circuits can provide driving signals to the light-emitting devices to make them emit light and achieve image display.

[0050] The light-emitting device includes a first electrode, a light-emitting functional layer, and a second electrode stacked sequentially along a direction away from the substrate. Optionally, the first electrode can be, for example, an anode, and the second electrode can be, for example, a cathode. The first electrodes of different light-emitting devices can be independently configured, thereby enabling independent driving of each light-emitting device. Therefore, the first electrode needs to be patterned during fabrication to correspond to a predetermined area where each light-emitting device is located.

[0051] In the fabrication of the first electrode, a continuous and uniform first electrode film is first formed. Then, photoresist is coated on top of the first electrode film and exposed through a photomask with a specific pattern. This causes a photochemical reaction in the illuminated areas of the photoresist, altering its solubility. A subsequent development process dissolves and removes the photoresist from the exposed areas (positive photoresist) or the unexposed areas (negative photoresist), forming a photoresist mask pattern on top of the first electrode film that matches the photomask pattern. Next, using this photoresist mask pattern as protection, the continuous and complete first electrode film deposited on the substrate is etched (dry or wet etching) to remove the first electrode film not protected by the photoresist. Finally, the photoresist mask is stripped off, precisely fabricating the desired first electrode pattern.

[0052] To accurately replicate the pattern on the photomask onto the photoresist layer, the uniformity of the photoresist is a key influencing factor. Photoresist comprises resin, photosensitizer (photoinitiator), solvent, and additives. Solvent constitutes the largest volume or mass percentage of the photoresist, typically ranging from 50% to 90%. Core materials such as photoinitiators and resins are usually solid powders and cannot be directly coated. The role of the solvent is to dissolve these solid substances, transforming them into a uniform, stable, and fluid liquid, thus facilitating the formation of a uniformly thick film on the surface of the patterned layer through processes such as spin coating, spray coating, or dip coating. However, the solvent has minimal impact on the photochemical reaction of the photoresist. Therefore, a pre-drying process is required before photoresist exposure to allow the solvent to precipitate out, preventing solvent evaporation and contamination of the exposure chamber during the exposure process. This also ensures uniform distribution of the photosensitizer, improving the exposure effect.

[0053] However, directly heating the substrate after applying photoresist into the cavity during the pre-drying process can easily cause Mura. Mura refers to macroscopic non-uniformity on the display panel (such as bright and dark stripes, color differences, spots, and other defects). This is because the cavity contains cold air, and the relatively low temperature causes the substrate placed inside the cavity to experience Mura due to the cooling effect.

[0054] Therefore, a vacuum drying process is required in the chamber before the material enters it. After photoresist coating, the photoresist contains a large amount of solvent, which has high surface tension and fluidity, negatively affecting the uniformity of film thickness. By reducing the pressure inside the chamber, the boiling point of the solvent is lowered under negative pressure, thereby accelerating the evaporation rate of the organic solvent and shortening the drying time.

[0055] Alternatively, the vacuum drying process can be completed within the vacuum chamber (VCD) of the vacuum drying equipment.

[0056] Figure 1This is a process flow diagram of vacuum decompression drying in some embodiments of this disclosure.

[0057] In some embodiments, such as Figure 1 As shown, the vacuum drying process can be divided into four stages:

[0058] Step 1: Low-speed decompression stage or initial decompression stage. This stage requires reducing the air pressure above the photoresist from atmospheric pressure to 1000Pa. This step requires controlling the valve opening to uniformly reach the set pressure value within 15-20 seconds to avoid solvent accumulation in local areas, which could lead to bubbles in the film layer.

[0059] In the initial decompression phase, the pressure decreases relatively slowly. During the initial transition from atmospheric pressure to low vacuum, the sudden drop in ambient pressure causes a rapid decrease in the solvent's boiling point. If the pressure is reduced too quickly, the solvent inside the film will instantly and violently boil and vaporize, generating a large number of bubbles. Simultaneously, rapid airflow disturbances can cause solvent accumulation in localized areas of the film, compromising the coating's smoothness. By uniformly and slowly reducing the pressure over 15-20 seconds using a valve, a gentle evaporation buffer period can be provided for the solvent, ensuring pressure balance between the film surface and its interior, thereby obtaining a smooth, bubble-free initially dried film.

[0060] Step 2: High-speed pressure reduction stage. This stage involves reducing the pressure from 1000Pa to 550-350Pa. During this stage, the valve needs to be able to quickly and accurately adjust to a specific opening degree within a short period of time.

[0061] When the pressure drops below 1000 Pa, the solvent on the membrane surface has initially stabilized. At this point, rapidly and precisely reducing the pressure can further increase the pressure difference between the solvent vapor pressure inside the membrane and the external ambient pressure. According to the principle of drying mass transfer, the greater the pressure difference, the stronger the driving force for solvent evaporation. This stage enables rapid and large-scale solvent removal without damaging the membrane structure, significantly shortening the overall drying cycle.

[0062] Step 3: Low-speed pressure reduction and holding stage. This stage reduces the gas pressure from 550-350Pa to 300-250Pa. The duration of this stage can be extended to improve the uniformity of film thickness and morphology. At the same time, the valve needs to be able to slowly and evenly increase the opening and closing degree so that the pressure change is almost equal percentage.

[0063] As drying progresses, the resistance to diffusion of moisture / solvent from the membrane interior to the surface gradually increases (i.e., entering the falling-rate drying phase). If the pressure is continued to drop rapidly at this point, it can lead to over-drying of the membrane surface or even film formation (pseudo-drying), hindering the escape of internal solvent and causing uneven membrane thickness. By extending this phase and maintaining a nearly uniform percentage of slow pressure reduction, an extremely stable mass transfer driving force can be maintained. This allows the solvent in all regions of the membrane to migrate outward uniformly and synchronously, effectively improving the uniformity of membrane thickness and critical dimension (CD), and ensuring a perfect membrane cross-sectional profile (H / T profile).

[0064] Step 4: Final depressurization stage. In this stage, the gas pressure is finally reduced to 26 Pa to maximize the solvent evaporation rate, requiring a rapid valve response.

[0065] In the final stage of drying, only trace amounts or non-volatile residual solvents remain in the film. Reducing the pressure to an extremely low vacuum of 26 Pa lowers the boiling point of the residual solvents to an extremely low level, allowing them to reach their maximum evaporation rate at room temperature or slightly below room temperature. Rapid valve response is required at this stage to establish and maintain a high vacuum environment in a very short time, thoroughly removing deep-seated residual solvents and ensuring the purity, adhesion, and stability of the final film, as well as subsequent processes (such as exposure).

[0066] To implement the above-mentioned stages, a standard time-pressure curve can be set, and the valve opening and closing degree can be indirectly controlled according to the standard time-pressure curve to ensure that the air pressure change conforms to the standard pressure curve. The main factors affecting the actual time-pressure curve are:

[0067] Flow control characteristics of the valve body.

[0068] In some embodiments, the valve used is a butterfly valve. Figure 2A This is a schematic diagram of the butterfly valve in the closed state in some embodiments. Figure 2B This is a schematic diagram of the butterfly valve in the open state in some embodiments.

[0069] like Figure 2A As shown, the butterfly valve includes a baffle 01 and a flip shaft 02. The flip shaft 02 can drive the baffle 01 to flip around the straight line where the flip shaft 02 is located.

[0070] like Figure 2B As shown, by controlling the degree to which the baffle 01 is rotated by the rotating shaft 02, the opening and closing size of the valve can be controlled to achieve the basic requirements of pressure reduction, pressure stabilization and pressure increase in each segment within the tact time, but its flow regulation capability is limited.

[0071] For example, at the intermediate opening degree (30%-70%), the adjustment sensitivity is low, and the large fluctuations in valve flow indirectly affect the low-speed decompression stage of vacuum drying, thus generating bubbles. When the opening degree is greater than 90%, only stepped adjustment can be achieved, and smooth, continuous changes are not possible, making it difficult to achieve precise pressure control, thus preventing the solvent from evaporating in the ideal ultra-low vacuum environment.

[0072] ② The valve body's ability to track and provide feedback on real-time pressure.

[0073] During vacuum drying, solvent evaporation causes pressure changes within the system. In the initial depressurization stage, the high solvent concentration and rapid evaporation rate can lead to a pressure increase, necessitating timely evacuation. As the solvent concentration decreases, the evaporation rate slows, requiring a reduction in the evacuation volume. Furthermore, disturbances caused by aging or oil blockage of the vacuum pump can also affect evacuation efficiency; and the varying thickness of photoresist coatings on different film layers also contributes to pressure changes due to the total amount of solvent evaporation.

[0074] Therefore, the valve body's excellent flow control characteristics and its ability to strictly track the set pressure curve and provide real-time feedback to dynamically adjust the pressure within the system are key to ensuring efficient and uniform solvent evaporation.

[0075] In order to at least alleviate or solve one of the aforementioned technical problems, this disclosure provides a vacuum drying apparatus for removing solvents from photoresist.

[0076] Figure 3 This is a schematic diagram of the structural composition of a vacuum drying apparatus in some embodiments of this disclosure.

[0077] In some embodiments, such as Figure 3 As shown, the vacuum drying equipment disclosed herein includes: a vacuum chamber 10, a flow pipe 20, a ball valve 30, and a drive device 40.

[0078] The flow channel 20 is connected to the vacuum chamber 10.

[0079] The ball valve 30 is rotatably disposed in the flow pipe 20. The ball valve 30 has an exhaust passage 30a, and the cross-section of the exhaust passage 30a is fan-shaped.

[0080] The drive device 40 is connected to the ball valve 30 for driving the ball valve 30 to rotate and adjust the opening degree of the ball valve 30, thereby adjusting the gas flow rate. The opening degree refers to the ratio of the overlapping conductive area of ​​the exhaust channel 30a and the flow pipe 20 to the cross-sectional area of ​​the exhaust channel 30a in the ball valve 30.

[0081] This embodiment employs a fan-shaped design for the ball valve 30 opening, resulting in a smoother, more linear transition between the valve opening and the flow area, providing a physical basis for subsequent precision pressure control. This solves the technical problem that, in the initial opening phase of the butterfly valve, the flow area increases rapidly and non-linearly, easily causing sudden pressure changes within the vacuum chamber 10 (excessive pumping leading to photoresist bubbling).

[0082] In some embodiments, the change in the opening degree of the ball valve 30 is linearly proportional to the change in the theoretical gas flow rate within the flow pipe 20.

[0083] In this embodiment, the linear proportional relationship provided by the sector channel means that the opening control of the ball valve 30 no longer requires a complex nonlinear compensation algorithm, which greatly reduces the control difficulty and improves the predictability and control accuracy of the valve response.

[0084] In some embodiments, such as Figure 3 As shown, the vacuum drying equipment also includes a control module 50, which is configured to control the drive device 40 to rotate the ball valve 30 to adjust the opening degree of the ball valve 30 during the removal of photoresist solvent, and to use the following multi-segment basic opening degree as the control reference:

[0085] During the initial pressure reduction phase, the opening degree of the control ball valve 30 is in the range of 5% to 15%.

[0086] During the rapid pressure reduction phase, the opening degree of the control ball valve 30 is in the range of 30% to 60%.

[0087] During the pressure reduction and holding phase, the opening degree of the control ball valve 30 is in the range of 10% to 25%.

[0088] During the final pressure reduction stage, the opening degree of the control ball valve 30 is in the range of 80% to 100%.

[0089] The embodiments of this disclosure divide the solvent removal process into four stages and set a specific basic opening range for each stage.

[0090] In the initial decompression stage, the valve opening is small. This slight opening prevents excessive suction from causing bubbles or splashing on the wet film. In the rapid decompression stage, the valve opening is larger. This large opening, combined with a high pumping speed, quickly removes a large amount of solvent, shortening the process time. In the decompression holding stage, the valve opening is reduced. Closing the valve slightly increases flow resistance, and the vacuum pump helps maintain stable pressure at low levels, allowing sufficient time for the solvent to diffuse from the film's interior to the surface. In the final decompression stage, the valve is fully opened for extreme suction, completely removing any remaining solvent.

[0091] This disclosure, through a segmented base aperture, perfectly matches the hydrodynamic requirements during the photoresist drying process, effectively preventing Mura defects.

[0092] In some embodiments, such as Figure 3 As shown, the vacuum drying equipment also includes a vacuum pumping device 60, which is connected to the vacuum chamber 10. The vacuum pumping device 60 is configured to sequentially perform vacuum pumping operations in the initial decompression stage, rapid decompression stage, decompression holding stage, and final decompression stage, and to pump air according to the following parameters:

[0093] During the initial decompression phase, the goal is to reduce the air pressure in the vacuum chamber 10 from atmospheric pressure to 900-1200 Pa within 15-25 seconds.

[0094] During the rapid decompression phase, the goal is to reduce the gas pressure in the vacuum chamber 10 from 900-1200 Pa to 250-300 Pa within 6-10 seconds.

[0095] During the pressure reduction and holding phase, the goal is to maintain the gas pressure in the vacuum chamber 10 at 250~300Pa for 12~18s.

[0096] During the final decompression stage, the goal is to reduce the pressure in the vacuum chamber 10 from 250-300 Pa to 20-30 Pa within 4-15 seconds.

[0097] This disclosure further sets specific pressure thresholds and evacuation time windows based on the above four stages. Specifically, this disclosure translates abstract control logic into specific process parameters to match the standard time-pressure curve. Ensuring accurate alignment with the time-pressure curve is crucial for guaranteeing the drying consistency of each batch of photoresist, directly determining the yield of the display panel manufacturing process.

[0098] In some embodiments, the control module 50 includes a PID controller, which is configured to acquire the actual air pressure of the vacuum chamber 10 in real time, obtain the deviation value between the actual air pressure of the vacuum chamber 10 and a preset standard pressure curve, and dynamically adjust the PID parameters according to the deviation value to adjust the opening of the ball valve 30 and / or control the vacuum pumping device 60 through the drive device 40, so that the deviation value is stabilized within a preset threshold error range. The PID parameters include at least one of the proportional gain parameter P, integral gain parameter I, and derivative gain parameter D.

[0099] This disclosure introduces a PID controller to collect the deviations between the actual air pressure and actual voltage and the standard curve, and then dynamically adjusts the P, I, and D parameters according to the deviations, and controls the ball valve 30 and / or the vacuum device 60 to achieve the requirements of the four stages in the aforementioned steps, thereby ensuring that the actual pressure conforms to the standard time-pressure curve.

[0100] In actual production, the state of equipment and materials fluctuates. The PID controller can correct the error of the actual pressure in real time based on the target pressure reduction curve in the aforementioned embodiment, ensuring that the actual pressure curve closely follows the standard curve, which greatly improves the anti-interference ability of the equipment and the stability of the process.

[0101] In some embodiments, during the initial decompression phase, the PID controller employs a high integral gain parameter I that adapts to the linear buck convergence criterion.

[0102] During the rapid decompression phase, the PID controller employs a high proportional gain parameter P that meets the dynamic tracking requirements and a differential gain parameter D that meets the preset damping requirements.

[0103] During the pressure reduction and holding phase, the PID controller uses a low proportional gain parameter P and a high integral gain parameter I to maintain dynamic balance of the chamber pressure.

[0104] During the final decompression stage, the PID controller uses a low proportional gain parameter P and a dynamically fine-tuned integral gain parameter I to bring the pressure in the vacuum chamber 10 to converge and stabilize at 20~30 Pa.

[0105] Considering that the physical properties of vacuum drying are completely different at different stages, the embodiments of this disclosure have customized specific combinations of PID parameters for the four different stages.

[0106] In the initial decompression phase, a high pressure (I) can quickly eliminate initial static errors and rapidly establish a vacuum. In the rapid decompression phase, a high pressure (P) and moderate pressure (D) are used; high P accelerates the response speed, and high D provides damping to prevent drastic pressure fluctuations during rapid descent. In the decompression holding phase, a low pressure (P) and high pressure (I) are used; low P prevents the system from overreacting to small fluctuations, and high pressure ensures the pressure is firmly locked at the target value, eliminating steady-state errors. In the final decompression phase, dynamic fine-tuning of pressure (I) is employed. Specifically, at extremely low pressures, the system is prone to oscillations; dynamic fine-tuning of I enables smooth limit convergence.

[0107] Figure 4A and Figure 4B This is a schematic diagram of the structure of the ball valve 30 in some embodiments of this disclosure.

[0108] In some embodiments, such as Figure 4A and Figure 4B As shown, the exhaust channel 30a is a through hole that penetrates the ball valve 30, and the through hole is formed by the two side walls and the arc surface connecting the two side walls.

[0109] Optionally, the vacuum drying equipment also includes at least two retaining rings 70, which are fixedly connected to the inner wall of the flow pipe 20. The retaining rings 70 are arranged sequentially along the extension direction of the flow pipe 20, and the ball valve 30 is rotatably installed and limited between the two retaining rings 70.

[0110] Among them, Figure 4A In this configuration, the exhaust passage 30a is aligned with the flow pipe 20, at which point the valve opening reaches 100%. Figure 4B In the middle, the exhaust passage 30a is perpendicular to the direction of the flow pipe 20, and at this time the valve opening is 0%, that is, the flow pipe 20 is closed.

[0111] Figure 5 This is a schematic diagram of the structure of the ball valve 30 in some other embodiments of this disclosure.

[0112] In other embodiments, such as Figure 5 As shown, the exhaust channel 30a has a V-shaped cut, which is formed by the two side walls.

[0113] In this embodiment, the specific geometry of the exhaust channel 30a is defined as either a through-hole or a V-shaped notch. A V-shaped notch offers better flow regulation resolution at small openings, making it suitable for precise fine-tuning during the initial decompression phase. A circular arc-shaped through-hole, on the other hand, is more suitable for rapid decompression during high-flow-rate phases.

[0114] In some embodiments, such as Figure 4A , Figure 4B As shown, the geometric center of the ball valve 30 is located in the internal region of the exhaust passage 30a.

[0115] This disclosure specifies that the geometric center of the ball valve 30 is located in the internal region of the exhaust channel 30a, i.e., an eccentric design. The eccentric design can change the torque and flow characteristics curves of the valve during rotation, making the valve adjustment within a specific opening range more linear or more targeted, and further optimizing the flow field distribution.

[0116] In some embodiments, combined with Figure 4A As shown, the drive device 40 is configured to drive the ball valve 30 to rotate in a first plane about a first axis as the rotation axis. The first axis is perpendicular to the extension direction of the flow pipe 20 and perpendicular to the extension direction of the exhaust passage 30a. The first plane is parallel to the extension direction of the flow pipe 20 and parallel to the extension direction of the exhaust passage 30a.

[0117] The flow pipe 20 has an elliptical cross-section, and the ball valve 30 is an ellipsoid; or the flow pipe 20 has a circular cross-section, and the ball valve 30 is a sphere. Figure 4A The following explanation uses ball valve 30 as an example, which has a ball as its body.

[0118] The embodiments disclosed herein employ a ball valve 30 or an ellipsoidal ball valve 30. This specific spatial geometric fit ensures that the fan-shaped exhaust channel 30a can sweep across the cross section of the flow pipe 20 evenly and smoothly during rotation, avoiding mechanical jamming and dead zones in the flow field.

[0119] In some embodiments, such as Figure 4A , Figure 4B and Figure 5 As shown, the central angle ω of the sector is 30°~120°, for example, it can be 45°, 60°, 75°, 90°, or 100°. And / or, the ratio of the cross-sectional area of ​​the exhaust channel 30a to the cross-sectional area of ​​the flow pipe 20 is 30%~60%, for example, 50%.

[0120] This embodiment of the disclosure parameterizes the dimensions of the fan-shaped channel. If the central angle of the fan is too small, the maximum flow rate will be insufficient; if the angle is too large, the linear adjustment advantage of the fan-shaped design will be lost. The area ratio between the exhaust channel 30a and the flow pipe 20 ensures that the valve will not become a bottleneck in the entire vacuum pipeline when fully open.

[0121] In a specific example, to improve the evaporation effect of the solvent under various stages of chamber depressurization, and to efficiently dry the photoresist to avoid the negative impact of defects such as bubbles and cracks on film thickness uniformity, the embodiments of this disclosure employ... Figure 5 The V-type open ball valve 30 and PID controller shown realize the pressure reduction drying process.

[0122] The V-shaped ball valve 30 used in this example has a V-shaped cut at its edge. The included angle ω of the V-shaped cut can be machined to, for example, 90°. The ball valve 30 is rotated by the driving force of the driving device 40, thereby changing the overlapping area of ​​the exhaust channel 30a and the flow pipe 20, and adjusting the flow rate of the airflow to achieve the effect of pressure control.

[0123] The flow characteristic of the V-shaped ball valve 30 is that the change in the relative flow rate Q of the gas caused by the change in the relative opening L of the ball valve 30 due to the adjustment of the ball valve 30 rotation is directly proportional to the change in the relative flow rate Q of the gas. It almost coincides with the ideal equal percentage characteristic curve.

[0124] Figure 6 These are simulation effect diagrams of some embodiments of this disclosure.

[0125] Figure 6 In the figures, the experimental study uses curves from the embodiments of this disclosure, while the equal percentage flow characteristic uses theoretical curves. The horizontal axis represents the valve relative opening (%), from 0% (fully closed) to 100% (fully open). The vertical axis represents the relative flow coefficient (%), representing the ratio of the actual flow capacity of the fluid through the valve to the maximum flow rate at a specific opening. The higher the value, the greater the flow rate at that opening.

[0126] The square-point (equal percentage flow characteristic) curve is the theoretical standard curve. The so-called "equal percentage characteristic" means that the flow rate change caused by a unit change in stroke is directly proportional to the flow rate at that point. Simply put, at small openings, the flow rate changes slowly (small amplification factor), resulting in smooth adjustment; at large openings, the flow rate changes rapidly (large amplification factor), resulting in sensitive adjustment. This characteristic is very suitable for pressure control or vacuum control, ensuring stability under both low and high loads. The star-point (experimental research) curve is a line connecting data points obtained from actual tests.

[0127] like Figure 6 As shown, the data points from the experimental study almost perfectly fall on the theoretical curve of the equal percentage flow characteristic. This proves that the design of the ball valve 30 is very successful, and its actual physical performance fully meets the expected equal percentage regulation characteristics.

[0128] Therefore, it can be seen that the curve of ball valve 30 is relatively flat in the 0%-50% opening range, indicating that the valve's flow regulation is relatively "slow" or precise at this time, suitable for fine-tuning and less likely to cause system oscillation. In the 80%-100% opening range, the curve of ball valve 30 rises sharply, indicating that the valve is very sensitive to flow regulation at this time; even a slight rotation of the angle will result in a significant increase in flow, suitable for rapid air extraction or pressure relief.

[0129] Therefore, for vacuum drying equipment in the initial stage of vacuum control (requiring large flow rate and rapid gas extraction) and the later stage (requiring small flow rate and precise pressure stabilization), the valves provided in this disclosure can provide suitable gain, and when combined with a PID controller, they can achieve excellent control results.

[0130] Specifically, the gas flow rate changes gradually when the valve is open between 5% and 15%, preventing mura caused by excessively rapid solvent evaporation. When the valve is open between 30% and 60%, it can rapidly and accurately reduce pressure, shortening the tact time. During the pressure reduction and holding phase, the valve opening can be reduced to 10% to 25%, at which point the pressure decreases at an approximately equal percentage rate, ensuring gradient solvent evaporation. Therefore, this phase can effectively improve film uniformity and H / T profile by adjusting the pressure-time slope to match the rate of film stress release. When the valve is open between 80% and 100%, it can be rapidly depressurized to 26 Pa with a vacuum pump, and its high-resolution adjustment capability can control vacuum pressure fluctuations within ±0.5 Pa.

[0131] Figure 7 This is a schematic diagram of the connection relationship of the PID controller in some embodiments of this disclosure.

[0132] like Figure 7As shown, the PID controller continuously measures the actual pressure of the vacuum chamber 10 and uses the actual pressure as the input value. It calculates the error between the input value and the set standard pressure, outputs the corresponding standard pressure value according to the error, and simultaneously adjusts the proportional, integral and derivative parameters to control the opening of the ball valve and the vacuum pumping device. At the same time, it controls the drive device 40 and the vacuum pumping device 60 to make the actual pressure of the vacuum chamber 10 track and match the set standard pressure as quickly and accurately as possible.

[0133] Figure 8 This is a comparison chart of time-pressure curves in some embodiments of this disclosure. Figure 8 A comparison diagram showing the effect of setting the standard time-pressure curve and the actual time-pressure curve is presented.

[0134] like Figure 8 As shown, in the scenario of photoresist organic solvent vacuum drying, the V-shaped ball valve 30 can continuously rotate the valve core according to the signal fed back by the pressure sensor to dynamically adjust the pumping pressure.

[0135] In the initial low-speed decompression stage, small deviations are eliminated by high I (integral) gain, achieving a linear decrease in pressure (e.g., 60 Pa / s) and eliminating local bubbles in the film layer caused by pressure strain.

[0136] During the high-speed or rapid decompression phase, a high P (proportional) gain combined with a moderate D (derivative) gain can quickly influence the set pressure change. At the same time, a preset opening curve can be used to automatically accelerate the response, avoid overshoot, and result in a lower pressure value.

[0137] During the low-speed decompression holding phase, the uniformity control window can be extended by combining low P with high I gain, ensuring stable solvent evaporation.

[0138] During the final low-pressure stage, the system can switch to PID fine-tuning mode to avoid over-vacuuming and suppress external interference (such as vibration of the vacuum pump), precisely controlling the bottom pressure at 26Pa±0.5Pa.

[0139] Figure 8 The pressure reduction drying curve under feedback control shown in the figure compares the actual control effect with the preset control effect. As can be seen from the figure, the actual curve closely follows the standard curve, indicating that the tracking performance of the control module 50 is very good, and it can accurately complete the pressure reduction process according to the predetermined four stages (Step 1-4).

[0140] In this embodiment of the disclosure, the efficient feedback control of the PID controller can shorten the Tact Time of the vacuum drying equipment and increase the factory's production capacity. At the same time, since the PID controller dynamically matches the valve opening, the vacuum pump load can be adjusted as needed to reduce energy consumption and save costs.

[0141] As can be seen from the above, this disclosure achieves a linear correspondence between the opening degree and the air flow rate through the fan-shaped cross-section ball valve 30, and pre-sets a reference opening degree range for the four-stage pressure reduction process. The reference opening degree determines the basic pressure reduction rate of each stage. At the same time, a PID controller is used to dynamically fine-tune the actual opening degree of the ball valve 30 within the reference opening degree range of each stage, and compensate for the air pressure deviation in real time. Combined with the timing pressure index of the vacuum pumping device 60, it takes into account both the anti-bubbling and drying efficiency of photoresist drying.

[0142] Specifically, the V-shaped exhaust channel 30a and ball valve 30 used in this disclosure can cover the entire reduced pressure drying process using its equal percentage flow characteristics, matching the pressure control requirements of multiple stages. Simultaneously, through the integration of a PID control algorithm, it can strictly track the set pressure / time curve and adjust it in real time, achieving pressure negative feedback closed-loop control and ensuring controllable solvent evaporation.

[0143] In summary, this disclosure aims to improve the evaporation effect of the solvent during the vacuum drying process, avoid defects such as bubbles and cracks, and improve the uniformity of photoresist film thickness. It utilizes a designed V-shaped ball valve to achieve a constant percentage pressure adjustment throughout the entire process. Simultaneously, an integrated PID control module compares the pressure signal fed back from the vacuum pressure sensor with the pressure value of the set curve, outputting a corrected pressure value to dynamically track the pressure curve at all stages. Ultimately, this disclosure can improve the evaporation effect of the solvent under vacuum conditions at each stage of the chamber, achieving efficient drying of the photoresist and preventing defects such as bubbles and cracks from negatively impacting film thickness uniformity.

[0144] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A vacuum drying apparatus for removing solvent from photoresist, characterized in that, The vacuum drying equipment includes: Vacuum chamber; A flow channel is connected to the vacuum chamber; A ball valve is rotatably disposed within the flow pipe, and the ball valve has an exhaust passage with a fan-shaped cross-section. A driving device, connected to the ball valve, is used to drive the ball valve to rotate in order to adjust the opening degree of the ball valve, wherein the opening degree is the ratio of the overlapping conductive area of ​​the exhaust channel and the flow pipe to the cross-section of the exhaust channel.

2. The vacuum drying equipment according to claim 1, characterized in that, The change in the opening degree of the ball valve is linearly proportional to the change in the theoretical gas flow rate in the flow pipe.

3. The vacuum drying equipment according to claim 2, characterized in that, The vacuum drying equipment further includes a control module configured to control the drive device to rotate the ball valve to adjust the opening degree of the ball valve during the removal of photoresist solvent, using the following multiple basic opening degrees as control references: During the initial pressure reduction phase, the opening degree of the ball valve is controlled to be in the range of 5% to 15%. During the rapid pressure reduction phase, the opening degree of the ball valve is controlled to be in the range of 30% to 60%. During the pressure reduction and holding phase, the opening degree of the ball valve is controlled to be in the range of 10% to 25%. During the final pressure reduction stage, the opening degree of the ball valve is controlled to be between 80% and 100%.

4. The vacuum drying equipment according to claim 3, characterized in that, The vacuum drying equipment further includes a vacuum pumping device, which is connected to the vacuum chamber. The vacuum pumping device is configured to sequentially perform the initial decompression stage, the rapid decompression stage, the decompression holding stage, and the final decompression stage, and to pump air according to the following parameters: During the initial decompression phase, the goal is to reduce the air pressure in the vacuum chamber from atmospheric pressure to 900-1200 Pa within 15-25 seconds. During the rapid decompression phase, the goal is to reduce the gas pressure in the vacuum chamber from 900-1200 Pa to 250-300 Pa within 6-10 seconds. During the pressure reduction and holding phase, the goal is to maintain the gas pressure in the vacuum chamber at 250~300Pa for 12~18s. During the final decompression stage, the goal is to reduce the air pressure in the vacuum chamber from 250-300 Pa to 20-30 Pa within 4-15 seconds.

5. The vacuum drying equipment according to claim 4, characterized in that, The control module includes a PID controller, which is configured to collect the actual air pressure of the vacuum chamber in real time, obtain the deviation value between the actual air pressure of the vacuum chamber and a preset standard pressure curve, and dynamically adjust the PID parameters according to the deviation value to adjust the opening of the ball valve and / or control the vacuuming device through the drive device, so that the deviation value is stabilized within a preset threshold error range. The PID parameters include at least one of proportional gain parameter P, integral gain parameter I, and derivative gain parameter D.

6. The vacuum drying equipment according to claim 5, characterized in that, During the initial decompression phase, the PID controller employs a high integral gain parameter I that adapts to the linear buck convergence criterion. During the rapid decompression phase, the PID controller employs a high proportional gain parameter P that meets the dynamic tracking requirements and a differential gain parameter D that meets the preset damping requirements. During the pressure reduction and holding phase, the PID controller employs a low proportional gain parameter P and a high integral gain parameter I to maintain the chamber pressure in dynamic equilibrium. During the final decompression stage, the PID controller uses a low proportional gain parameter P and a dynamically fine-tuned integral gain parameter I to make the air pressure in the vacuum chamber converge and stabilize at 20~30Pa.

7. The vacuum drying apparatus according to any one of claims 1 to 6, characterized in that, The exhaust passage includes a through hole penetrating the ball valve, the through hole being enclosed by two side walls and an arc surface connecting the two side walls; And / or, the exhaust passage includes a V-shaped cut, which is enclosed by two side walls.

8. The vacuum drying apparatus according to any one of claims 1 to 6, characterized in that, The geometric center of the ball valve is located in the internal region of the exhaust passage.

9. The vacuum drying apparatus according to any one of claims 1 to 6, characterized in that, The drive device is configured to drive the ball valve to rotate in a first plane about a first axis as the rotation axis, the first axis being perpendicular to the extension direction of the flow pipe and perpendicular to the extension direction of the exhaust passage, and the first plane being parallel to the extension direction of the flow pipe and parallel to the extension direction of the exhaust passage. Wherein, the cross-section of the flow pipe is elliptical, and the ball valve is an ellipsoid; Alternatively, the cross-section of the flow channel is circular, and the ball valve is a ball.

10. The vacuum drying apparatus according to any one of claims 1 to 6, characterized in that, The central angle of the sector is 30°~120°; And / or, the ratio of the cross-sectional area of ​​the exhaust channel to the cross-sectional area of ​​the flow pipe is 30% to 60%.

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