Glue uniformizing method for spin-coating photoresist on substrate and glue uniformizing device thereof

Abstract

The invention relates to a spin coating method for spin coating of photoresist on a substrate and a spin coating device of the spin coating method, and belongs to the technical field of semiconductor manufacturing and micro-nano machining. The temperature of a spin-coating suction cup used for bearing the substrate is controlled to be a preset target temperature, and the preset target temperature is higher than the temperature of the environment where the spin-coating photoresist is located, so that the spin-coating photoresist is obtained by increasing the temperature of the center area, in close contact with the spin-coating suction cup, of the substrate. The present invention compensates for a change in film thickness of an annular region caused by warping of the annular region on the outer periphery of a substrate. According to the invention, the color ring effect can be fundamentally and actively eliminated or compensated, and the glue uniformizing uniformity of the substrate is improved.

Description

Technical Field

[0001] This invention application relates to the fields of semiconductor manufacturing and micro / nano fabrication technology, and in particular to a spin coating method and apparatus for spin coating photoresist onto a substrate. Background Technology

[0002] In the process of spin-coating photoresist onto glass substrates, due to the need for edge washing and other processes, as well as considerations such as reducing contact surfaces and preventing cross-contamination, the wafer stage is often smaller than the wafer size. When the glass substrate is supported on the wafer stage, the suspension of the substrate's outer periphery causes a slight sinking, which amplifies the film thickness non-uniformity generated during the spin coating process. For example... Figure 1 As shown, when using substrates made of specific materials such as glass, the thickness of the photoresist on the surface exhibits a clear regional distribution. The film thickness is relatively low in the central stage-supported area, and the transition between the two areas is not smooth but rather abrupt at the stage edge, resulting in a very distinct boundary between the two areas. In actual process inspection, the reflection of light changes at the junctions where the surface film thickness changes drastically, thus producing color textures that are visible to the naked eye.

[0003] Obviously, in actual semiconductor manufacturing processes, color rings can cause subsequent process abnormalities, resulting in a decrease in the yield of semiconductor device manufacturing. Currently, the industry has very limited solutions to this problem: (1) Increase the overall film thickness. By increasing the viscosity of the photoresist or increasing the rotation speed, the overall film thickness can be increased, so that the proportion of the absolute film thickness difference in the color ring area in the total film thickness decreases, making the color ring less visually obvious. However, this method is only a temporary solution, and the film thickness difference of the ring still exists objectively. More importantly, changing the film thickness will directly violate the design requirements of specific process steps, which is almost impossible in actual production; (2) Ignore the color ring problem. The existence of the color ring problem will compress the process window of subsequent processes (such as exposure and etching). When the process window is large, hoping that the subsequent process can tolerate this film thickness unevenness is a passive technical compromise with great process risk. Once the subsequent process window narrows or shifts, the color ring problem defect will immediately be converted into a batch yield loss. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for spin-coating photoresist onto a substrate, aiming to partially or completely solve the technical problems of color rings and uneven film thickness caused by high-speed rotation warping due to the heavy weight and high warpage of the substrate during existing spin-coating of photoresist onto glass substrates. This invention can fundamentally and actively eliminate or compensate for the color ring effect, improving the uniformity of substrate spin-coating. To achieve the above objective, this invention provides the following technical solution: In a first aspect, a method for spin-coating photoresist onto a substrate includes the following steps: During the spin coating of photoresist onto the substrate, the temperature of the spin coating chuck used to support the substrate is controlled at a preset target temperature, which is higher than the temperature of the environment where the spin coating photoresist is located. This is to compensate for the film thickness change in the annular region caused by the warping of the outer annular region of the substrate by raising the temperature of the central region of the substrate that is in close contact with the spin coating chuck.

[0005] In one or more technical solutions of this invention application, the substrate is a glass substrate; Alternatively, the target temperature may be 1°C to 20°C higher than the ambient temperature; Alternatively, the target temperature may be 1°C to 5°C higher than the ambient temperature.

[0006] In one or more technical solutions of this invention application, the spin coating process includes a step of rotating the substrate at high speed, and during the high-speed rotation step, the temperature of the spin coating chuck is controlled at the preset target temperature.

[0007] In one or more technical solutions of this invention application, the method further includes: preheating the coating suction cup to reach the preset target temperature before placing the substrate onto the coating suction cup.

[0008] In one or more technical solutions of this invention application, the method further includes maintaining the coating suction cup at the preset target temperature throughout the entire process of placing the substrate on the coating suction cup.

[0009] Secondly, a spin coating apparatus for spin-coating photoresist includes: A plastering suction cup for supporting substrates; A temperature control system, thermally coupled to the plating suction cup, is used to regulate the temperature of the plating suction cup; The controller is connected to the temperature control system; The controller is configured to, at least during the spin coating of photoresist onto the substrate, control the temperature control system to maintain the temperature of the spin coating chuck at a target temperature higher than the ambient temperature of the spin coating apparatus. The film thickness variation in the annular region caused by the warping of the outer annular region of the substrate is compensated by increasing the temperature of the central region of the substrate that is in close contact with the spin coater.

[0010] In one or more technical solutions of this invention application, the heat exchange unit of the temperature control system is at least one semiconductor refrigeration chip; Alternatively, the heat exchange unit of the temperature control system includes a fluid channel disposed inside the uniform adhesive suction cup, and the fluid channel is connected to an external constant temperature circulating cooling device.

[0011] In one or more of the technical solutions of this invention application, the temperature control system further includes a temperature sensor, which is disposed on the upper surface of the adhesive suction cup near its supporting substrate.

[0012] In summary, compared with the prior art, this invention application has the following beneficial technical effects: (1) In this application, a solution for photoresist coating based on active temperature compensation is proposed. Instead of passively accepting the uneven thermal field caused by substrate warping, a specific temperature gradient is artificially and in reverse established on the substrate surface by actively controlling the temperature of the photoresist chuck. This temperature gradient is used to adjust the local viscosity of the photoresist, thereby compensating for the film thickness difference caused by warping. Finally, a highly uniform film thickness distribution is achieved, effectively eliminating the warping and uneven film thickness problems in the substrate spin coating process, improving the process stability and yield of semiconductor device manufacturing, without increasing the photoresist film thickness or relying on subsequent process windows, thereby reducing production costs. It can be applied to process steps with small process windows, as well as to other large-size, flexible or special material substrates with similar warping problems, thereby improving the overall semiconductor process yield and efficiency.

[0013] (2) In this invention application, through the synergistic effect of the temperature control system and the controller, the high temperature target temperature of the spin coating chuck is precisely maintained in the spin coating photoresist process. The problem of color rings is not masked or ignored. Instead, the negative impact of warpage is directly offset by active and physical temperature compensation. The problem of substrate warpage and uneven film thickness is effectively suppressed, the cause of color rings is eliminated, the effect is significant, the uniformity is greatly improved, the core process parameters are not changed, and there is no need to change the type, viscosity or target film thickness of the photoresist. It is fully compatible with the existing process specifications (POR) and easy to introduce into the production line. It is not only applicable to glass substrates, but also applicable to any other large-size, flexible or special material substrates with warpage problems. The cost is controllable and easy to implement. The modification of the existing spin coating equipment mainly involves replacing or adding a temperature control chuck. The technology is mature, the cost is relatively low, and it is easy to implement and promote. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the color texture of a glass material substrate in the prior art; Figure 2 This is a schematic diagram of a spin coating apparatus for spin coating photoresist onto a substrate, as described in this invention application. Figure 3 This is a ring map of the wafer coating thickness at a preset target temperature of 22.4°C using a small-sized coating suction cup according to an embodiment of this invention. Figure 4This is a ring map of the wafer coating thickness at a preset target temperature of 23.0°C using a small-sized coating suction cup according to an embodiment of this invention. Figure 5 This is a ring map of the wafer coating thickness at a preset target temperature of 23.0°C using a large-size coating suction cup, according to another embodiment of this invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0016] In the description of this invention application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0017] In the description of this application, the substrate includes all semiconductor devices or flat panel displays, or includes a substrate having circuit patterns. Exemplarily, the substrate may be a wafer, a glass substrate, or an organic substrate, etc., and this application does not limit this.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0019] In this invention application, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an integral molding, or an integrated unit; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] To make the objectives, technical solutions, and advantages of this invention application clearer, the technical solutions in the embodiments of this invention application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention application without creative effort are within the scope of protection of this invention application.

[0021] In compound semiconductor devices, besides silicon wafers, glass wafers are also commonly used as substrates. Due to the advantages of glass wafers in terms of insulation and other properties, glass wafers and silicon wafers cannot be substituted for each other. In 8-inch and 12-inch wafers, due to the needs of edge washing processes and considerations such as reducing contact surfaces to prevent cross-contamination, the wafer stage is often smaller than the wafer size. Therefore, the wafer stage only supports a circular area of ​​about 1 / 3 to 1 / 2 of the wafer's diameter. When a glass substrate is supported on the wafer stage, due to the difference in density and elastic modulus between the glass substrate and the silicon substrate, the slight sinking caused by the outer periphery suspension is more significant than that of the silicon substrate, thus amplifying the film thickness non-uniformity generated during the spin coating process.

[0022] like Figure 1 As shown, when using substrates made of specific materials such as glass, and spin-coating the substrate at a speed of 1000-4000 rpm, the thickness of the photoresist on the surface exhibits a clear regional distribution. The thickness of the film in the central stage-supported region is relatively low, approximately 890-900 nm, while the thickness of the film in the outer, suspended region is between 910-930 nm. Furthermore, the transition between these two regions is not smooth but rather abrupt at the stage edge, resulting in a very distinct boundary between them. In actual process inspection, the reflection of light changes at the boundary where the surface film thickness changes drastically, thus producing color textures that are visible to the naked eye.

[0023] Analysis suggests that the underlying reasons may be as follows: (1) The change in force causes stress changes in the wafer substrate at the edge of the stage, which in turn affects the distribution of the surface film layer; (2) The warping of the glass substrate itself will change the radial flow path of the photoresist under centrifugal force; (3) The change in the shape of the substrate may cause changes in the contact force distribution between its bottom and the vacuum chuck, resulting in differences in thermal conductivity, etc.

[0024] Given the limitations of the manufacturing process, the existing rotating support structure is not suitable for modification. To ensure and improve the uniformity of the surface film thickness and eliminate visible colored textures under illumination, we provide a temperature-compensated film thickness compensation scheme. By applying influence to the central region of the substrate through the stage, we not only adjust the surface film thickness but also slow down the changes in surface film thickness, thereby avoiding drastic changes in film thickness at the substrate position on the stage edge and suppressing colored textures caused by abrupt changes in film thickness.

[0025] In a first aspect, a method for spin-coating photoresist onto a substrate includes the following steps: During the spin coating of photoresist onto the substrate, the temperature of the spin coating chuck used to support the substrate is controlled at a preset target temperature, which is higher than the temperature of the environment where the spin coating photoresist is located. This is to compensate for the film thickness change in the annular region caused by the warping of the outer annular region of the substrate by raising the temperature of the central region of the substrate that is in close contact with the spin coating chuck.

[0026] In one or more embodiments of this invention, before spin coating, a temperature sensor (exemplarily a thermocouple sensor or an infrared temperature detector) installed in the spin coating chuck can monitor the current temperature of the spin coating chuck in real time. Based on the monitoring results, a feedback control loop adjusts the heat exchange unit (e.g., including circulating cooling fluid and circulating hot fluid) to ensure the spin coating chuck reaches the preset target temperature. For example, when the current temperature is higher than the preset target, the heat exchange unit is activated to cool down to the preset target temperature; conversely, when the current temperature is lower than the preset target, the heat exchange unit is activated to heat up. Simultaneously, the temperature gradient can be monitored to ensure that an excessively high heating rate is not formed, thereby preventing the substrate from warping due to thermal stress and ensuring the stability of the spin coating process.

[0027] In one or more embodiments of this invention application, during the spin coating process, the rotation speed is controlled in stages, including an initial low-speed stage (100-500 rpm) to uniformly coat the photoresist, a medium-speed stage (500-1000 rpm) to promote diffusion, and a high-speed stage (1000-3000 rpm) to achieve uniform coating, while maintaining the preset target temperature, which is higher than the temperature of the environment where the spin-coated photoresist is located. For example, the preset target temperature can be set to 1-25°C above the ambient temperature, such as 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, etc. This invention application does not impose any limitations on this comparison.

[0028] In one or more embodiments of this invention, the substrate will warp under high-speed rotation. Specifically, since the substrate (such as a glass substrate) has higher quality and initial warp than a traditional silicon substrate, the centrifugal force will amplify the bending deformation of the substrate during the high-speed rotation stage of the spin-coating photoresist process (e.g., when the rotation speed reaches 1500-4000 rpm), resulting in dynamic warping on the substrate surface. This interferes with the radial flow and uniform distribution of the photoresist, which macroscopically manifests as a colored ring-shaped uneven film thickness area, which may lead to subsequent semiconductor process abnormalities and reduced device yield.

[0029] In one or more embodiments of this invention application, after spin coating, the uniformity of photoresist film thickness is verified using a film thickness measurement device (such as a reflectance spectrometer or film thickness gauge). Specifically, by performing multi-point sampling measurements on the substrate surface, the average film thickness, standard deviation, and maximum / minimum difference are calculated. The measurement data can be analyzed using image processing software to generate a film thickness distribution heat map, identify potential color ring positions, and adjust the preset target temperature or rotation speed strategy accordingly, thereby ensuring that the film thickness uniformity meets the process requirements and improving the overall process reliability.

[0030] In this invention application, by actively controlling the temperature of the spin coater to a preset target temperature higher than the ambient temperature of the spin-coated photoresist, during the high-speed rotation of the substrate (e.g., 1000-4000 rpm), the central region of the substrate is in close contact with the high-temperature spin coater, and the heat is rapidly conducted away, causing the temperature of the substrate portion and photoresist in the central region to rise. The radial outflow velocity of the photoresist under centrifugal force increases, which helps to maintain the amount of photoresist in the central region. At the same time, the substrate edge warps, forming a heat-insulating air gap between the annular region and the spin coater. The substrate portion and photoresist in the annular region cannot effectively exchange heat with the high-temperature spin coater, and its temperature will be maintained near the high ambient temperature. The photoresist has a relatively high viscosity and good fluidity, which helps the photoresist to spread smoothly and fill any depressions that may be formed. This forms a "holding" effect of the high-temperature spin coater on the amount of photoresist in the central region of the substrate, which precisely compensates for the excessive "loss" effect caused by warping in the annular region and avoids the formation of colored rings or annular areas with excessive film thickness.

[0031] In this invention application, by actively controlling the temperature of the spin coating chuck to a preset target temperature higher than the ambient temperature of the spin-coated photoresist, the photoresist is uniformly distributed on the substrate surface, avoiding the formation of color rings or annular areas with excessive film thickness, thereby achieving overall film thickness uniformity. This method is applicable to glass substrates or other large-size, flexible, or special material substrates with similar warping problems, thereby fundamentally and actively eliminating or compensating for the color ring effect and achieving overall film thickness uniformity.

[0032] This invention proposes a photoresist spin coating solution based on active temperature compensation. Instead of passively accepting the thermal unevenness caused by substrate warpage, it actively controls the temperature of the spin coating chuck to artificially and inversely establish a specific temperature gradient on the substrate surface. This temperature gradient is used to adjust the local viscosity of the photoresist, thereby compensating for the film thickness difference caused by warpage. Ultimately, a highly uniform film thickness distribution is achieved, effectively eliminating warpage and uneven film thickness problems during substrate spin coating of photoresist. This improves the process stability and yield of semiconductor device manufacturing without increasing the photoresist film thickness or relying on subsequent process windows, thus reducing production costs. Furthermore, it is applicable to process steps with small process windows, as well as other large-size, flexible, or special material substrates with similar warpage problems, thereby improving the overall semiconductor process yield and efficiency.

[0033] In one or more technical solutions of this invention application, the substrate is a glass substrate; or, the target temperature is 1°C to 20°C higher than the ambient temperature; or, the preset target temperature is 1°C to 5°C higher than the ambient temperature.

[0034] In one or more embodiments of this invention application, preferably, the substrate is a glass substrate. Of course, any other large-sized and / or flexible substrate that will warp under high-speed rotation (such as flexible organic substrates, ceramic substrates, or composite material substrates) is also within the scope of protection of this invention application, which can extend the applicability of the above-mentioned homogenization solution in the semiconductor and related fields.

[0035] In one or more embodiments of this invention, the preset target temperature can be set to 1-20°C higher than the temperature of the environment where the spin-coated photoresist is located, for example, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C, etc. Preferably, the preset target temperature can be set to 1-5°C higher than the temperature of the environment where the spin-coated photoresist is located, etc., and this invention does not limit this. It should be noted that the specific temperature can also be optimized and adjusted according to the substrate material, environmental conditions, and process requirements to achieve a better or optimal thermal shrinkage effect and warpage compensation.

[0036] In one or more technical solutions of this invention application, the spin coating process of photoresist includes a step of rotating the substrate at high speed, and during the high-speed rotation step, the temperature of the spin coating chuck is controlled at the preset target temperature.

[0037] In this invention application, one of the key aspects of the spin coating solution is that, during the spin coating process, especially during the high-speed rotation of the substrate, the temperature of the spin coating chuck is actively controlled to a preset target temperature higher than the ambient temperature. Specifically, a real-time temperature feedback system (such as a thermocouple sensor or infrared temperature detector) integrated into the spin coating chuck continuously monitors the surface temperature of the chuck. A closed-loop negative feedback control mechanism dynamically adjusts the operating state of the heat exchange unit based on the monitored temperature data to maintain the temperature of the spin coating chuck stable at the preset target temperature (1-5°C higher than the ambient temperature). For example, when the temperature deviation of the spin coating chuck exceeds ±0.3°C, the corresponding heat exchange unit is activated to ensure that the temperature of the spin coating chuck remains essentially constant.

[0038] In this invention application, it is necessary to control the temperature of the spin coater to a preset target temperature during the high-speed rotation step. During the high-speed rotation step of the substrate (such as a glass substrate), by maintaining the spin coater at the preset target temperature (higher than the ambient temperature), the high-temperature heat conduction in the center of the substrate and the flow of photoresist in the warped area of ​​the substrate are promoted. This ensures the tightness of the substrate and the spin coater, improves the uniformity of vacuum adsorption of the substrate, optimizes the discrete distribution of photoresist under centrifugal force, significantly reduces the film thickness fluctuation, and improves the overall spin coat quality and the accuracy of subsequent photolithography processes without increasing the complexity of the equipment or the processing time.

[0039] In one or more technical solutions of this invention application, the method further includes: preheating the coating suction cup to reach the preset target temperature before placing the substrate onto the coating suction cup.

[0040] In another embodiment of this invention, the preset temperature is maintained throughout the entire process of the substrate being carried on the stage, rather than at a specific rotation speed.

[0041] In one embodiment of this invention, before placing the substrate onto the spin coater, a preheating operation is performed to bring the spin coater to a preset target temperature higher than the ambient temperature in advance. This establishes a stable temperature environment immediately when the substrate contacts the spin coater. The preheating process helps to strengthen the tight adhesion between the substrate and the spin coater during the subsequent spin coating process (especially during the high-speed rotation stage), regulate the viscosity gradient and flow behavior of the photoresist, actively eliminate or compensate for the color ring effect, and reduce or avoid excessive film thickness in the annular region.

[0042] In one or more of the technical solutions of this invention application, the target temperature is higher than the dew point temperature of the environment.

[0043] like Figure 2 As shown, in a second aspect, a spin coating apparatus for spin-coating photoresist includes: 100 for coating suction cups used to support substrates; The temperature control system 200 is thermally coupled to the plating suction cup 100 and is used to regulate the temperature of the plating suction cup 100. Controller 300 is connected to the temperature control system 200; The controller is configured to, at least during the spin coating of photoresist onto the substrate, control the temperature control system to maintain the temperature of the spin coating chuck at a target temperature higher than the ambient temperature of the spin coating device, so as to compensate for the film thickness change in the annular region caused by the warping of the outer annular region of the substrate by raising the temperature of the central region of the substrate that is in close contact with the spin coating chuck.

[0044] In one or more embodiments of this invention application, the controller can be a PLC (Programmable Logic Controller) or a PID (Proportional-Integral-Derivative) temperature controller. The PLC has high programmability and robustness and is suitable for integrated control of complex processes, while the PID temperature controller achieves rapid response and stable adjustment to temperature deviations through proportional, integral and derivative algorithms. The controller and the temperature control system can be connected through a communication interface.

[0045] In this invention application, a temperature control system is configured using a controller (such as a PLC or PID temperature controller) to actively adjust and maintain the temperature of the spin coating chuck at a target temperature higher than the ambient temperature of the spin coating device during the spin coating process on the substrate. This eliminates mechanical interference from the radial flow path of the photoresist and thermodynamic issues caused by the poor thermal conductivity of the gap air, resulting in uneven temperature distribution on the substrate surface (higher temperature in the central area and lower temperature in the annular warped area). This promotes uniform distribution of the photoresist on the substrate surface, avoiding the formation of colored rings or annular areas with excessively high film thickness, thereby achieving overall film thickness uniformity. Specifically: During high-speed rotation, the central region of the substrate is in close contact with the high-temperature spin coater, and heat is rapidly conducted away. This raises the temperature of the substrate and photoresist in the central region, increasing the radial outflow velocity of the photoresist under centrifugal force, which helps maintain the amount of photoresist in the central region. Simultaneously, warping occurs at the substrate edges, creating a heat-insulating air gap between the annular region and the spin coater. The substrate and photoresist in the annular region cannot effectively exchange heat with the high-temperature spin coater, and their temperature remains near the high ambient temperature. The relatively high viscosity and good fluidity of the photoresist facilitate its smooth spread and fill any potential depressions. In this way, the "holding" effect of the high-temperature spin coater on the amount of photoresist in the central region of the substrate effectively compensates for the excessive "loss" effect caused by warping in the annular region, avoiding the formation of colored rings or annular areas with excessively high film thickness. This achieves overall film thickness uniformity and is suitable for glass substrates or other large-size, flexible, or special material substrates with similar warping problems. It can fundamentally and actively eliminate or compensate for the colored ring effect. Finally, after spin coating, a substrate with highly uniform film thickness and no obvious colored rings can be obtained.

[0046] In this invention application, through the synergistic effect of the temperature control system and controller, the high-temperature target temperature of the spin coating chuck is precisely maintained in the spin coating photoresist process. This completely avoids masking or ignoring the color ring problem, instead directly offsetting the negative impact of warpage through active, physical temperature compensation. This effectively suppresses substrate warpage and uneven film thickness, eliminating the cause of color rings, resulting in significant improvements in uniformity. It does not change the core process parameters, nor does it require altering the type, viscosity, or target film thickness of the photoresist. It is fully compatible with existing process specifications (POR), easy to implement in production lines, and applicable not only to glass substrates but also to any other large-size, flexible, or special-material substrates with warpage issues. The cost is controllable, and implementation is easy. Modifications to existing spin coating equipment mainly involve replacing or adding a temperature-controlled chuck. The technology is mature, relatively low-cost, and easy to implement and promote.

[0047] In one or more technical solutions of this invention application, the heat exchange unit of the temperature control system is at least one semiconductor refrigeration chip; or, the heat exchange unit of the temperature control system includes a fluid channel disposed inside the uniform adhesive suction cup, the fluid channel being connected to an external constant temperature circulating cooling device.

[0048] In one or more embodiments of this invention, the temperature control system may include a heat exchange unit coupled to the spin coater chuck for heating or cooling the spin coater chuck. The heat exchange unit may include a thermoelectric cooler / peltier (TEC), which is small, fast-responding, has no moving parts, can precisely control the temperature to ±0.1℃, and can achieve bidirectional cooling and heating by changing the current direction, making it suitable for the rapid temperature response requirements in spin coating processes. Alternatively, the heat exchange unit may include a fluid channel embedded or attached to the inside or bottom of the spin coater chuck, and delivers cooling / heating liquid (such as water or ethylene glycol solution) through an external constant-temperature circulating water bath system to achieve uniform temperature distribution and greater temperature regulation, suitable for large-size substrates or high-power heat load scenarios. Of course, the selection of the heat exchange unit can also be optimized according to the specific process environment, cost, and accuracy requirements to ensure that the temperature of the spin coater chuck remains stable at a preset target temperature.

[0049] In one or more of the technical solutions of this invention application, the temperature control system further includes a temperature sensor, which is disposed on the upper surface of the adhesive suction cup near its supporting substrate.

[0050] In one or more embodiments of this invention, one or more temperature sensors are provided for real-time monitoring of the actual temperature of the spin coating chuck and transmitting the monitoring signal to the controller to achieve closed-loop temperature control. The temperature sensors are preferably thermocouples or platinum resistance thermometers. Thermocouples offer advantages such as fast response, wide measurement range (e.g., -50°C to 200°C), and durability, making them suitable for dynamic spin coating environments. Platinum resistance thermometers provide higher accuracy (e.g., ±0.1°C) and linear output, making them suitable for precise temperature feedback requirements. The temperature sensors can be embedded in the internal structure of the spin coating chuck body, or closely attached to its upper surface (near the substrate contact surface) in the central and / or edge regions, or distributed at multiple circumferential points to capture temperature gradients and / or uneven temperature distribution of the spin coating chuck, ensuring the representativeness and accuracy of the monitoring data. For example, in large-size spin coating chucks, multiple sensor arrays can be arranged (e.g., one in the center and four radially spaced), fixed with waterproof seals and thermally conductive materials to avoid vibration or photoresist contamination during spin coating affecting monitoring stability. This supports the controller in precisely adjusting the temperature control system, achieving stable maintenance of the spin coating chuck temperature at a preset target temperature.

[0051] In one or more embodiments of this invention, the temperature control system and controller can be electrically connected to form a closed-loop control mode to achieve precise temperature feedback and regulation. The temperature sensor can be electrically connected to the controller via an analog signal line or a digital communication interface to transmit the real-time monitored temperature data of the coating suction cup to the controller. The controller integrates a signal processing module (such as an A / D converter to convert analog signals into digital data). After receiving and parsing the temperature signal, it calculates the deviation from the preset target temperature according to a preset temperature control algorithm (such as PID control logic), calculates the control output, and uses a power amplifier circuit or drive interface to connect to the heat exchange unit of the temperature control system. The heat exchange unit's operating parameters (such as current intensity, polarity reversal, or fluid pump valve opening) are adjusted by regulating the magnitude (e.g., increasing the current to enhance heating / cooling intensity) and direction (e.g., reversing the current polarity to switch heating / cooling modes for a TEC module) of the current applied to the heat exchange unit. This allows for precise control of the temperature of the spin coater. The spin coater may further include a power module connected to a controller and temperature control system, providing a stable DC power supply (e.g., 12V or 24V) to support temperature regulation of the spin coater and maintain its temperature within a preset target temperature range. Example

[0052] like Figure 3 As shown, the annular map of the wafer coating thickness at a preset target temperature of 22.4℃ using a small-sized coating chuck shows that the film thickness in the central stage-supported area ranges from approximately 890 to 900 nm, while the film thickness in the outer suspended area ranges from approximately 910 to 930 nm. The film thickness uniformity is 2.4%, resulting in a colored ring effect. Furthermore, the transition between the two areas is not smooth but rather abrupt at the stage edge, making the boundary between the two areas very distinct.

[0053] like Figure 4 As shown, this is a ring map of the wafer coating thickness at a preset target temperature of 23.0℃ using a small-sized coating chuck; the film thickness ranges from approximately 890-900 nm in the central stage-supported area, while the film thickness ranges from approximately 910-924 nm in the outer suspended area, with a film thickness uniformity of 2.2%.

[0054] like Figure 5 As shown, the annular map of the wafer coating thickness at a preset target temperature of 23.0℃ using a large-size coating chuck shows that the film thickness in the central stage bearing area ranges from approximately 1040 to 1045 nm, while the film thickness in the outer suspended area ranges from approximately 1029 to 1040 nm, with a film thickness uniformity of 1.9%.

[0055] Therefore, compared to Figure 3 , Figure 4 The color ring effect still exists in it, but Figure 4 The color ring effect was somewhat suppressed and improved; compared to Figure 3 , Figure 5 The mid-color ring effect was largely suppressed and improved. Figure 5 The mid-color ring effect has been largely eliminated, proving the effectiveness of the spin coating method for photoresist spin coating on substrates proposed in this invention.

[0056] The technical features of the above embodiments can be combined in any way. In order to keep the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. Those skilled in the art will understand that the steps, measures, and schemes in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted; furthermore, other steps, measures, and schemes in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted; furthermore, the steps, measures, and schemes in the prior art that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. The above-described embodiments are merely examples of several implementation methods of the present disclosure, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the patent for the present disclosure. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present disclosure, and these all fall within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be determined by the appended claims.

Claims

1. A method for spin-coating photoresist onto a substrate, characterized in that, Includes the following steps: During the spin coating of photoresist onto the substrate, the temperature of the spin coating chuck used to support the substrate is controlled at a preset target temperature, which is higher than the temperature of the environment where the spin coating photoresist is located. This is to compensate for the film thickness change in the annular region caused by the warping of the outer annular region of the substrate by raising the temperature of the central region of the substrate that is in close contact with the spin coating chuck.

2. The method for spin-coating photoresist onto a substrate according to claim 1, characterized in that, The substrate is a glass substrate; Alternatively, the target temperature may be 1°C to 20°C higher than the ambient temperature; Alternatively, the target temperature may be 1°C to 5°C higher than the ambient temperature.

3. The spin coating method according to claim 1, characterized in that, The spin-coating process includes a step of rotating the substrate at high speed, and during the high-speed rotation step, the temperature of the spin coating chuck is controlled at a preset target temperature.

4. The spin coating method according to any one of claims 1-3, characterized in that, Also includes: Before placing the substrate onto the spin coater, the spin coater is preheated to reach the preset target temperature.

5. The spin coating method according to any one of claims 1-3, characterized in that, It also includes maintaining the coating suction cup at the preset target temperature throughout the entire process of placing the substrate on the coating suction cup.

6. A spin coating apparatus for spin coating photoresist onto a substrate, comprising: A plastering suction cup for supporting substrates; A temperature control system, thermally coupled to the plating suction cup, is used to regulate the temperature of the plating suction cup; The controller is connected to the temperature control system; The controller is configured to, at least during the spin coating of photoresist onto the substrate, control the temperature control system to maintain the temperature of the spin coating chuck at a target temperature higher than the ambient temperature of the spin coating device, so as to compensate for the film thickness change in the annular region caused by the warping of the outer annular region of the substrate by raising the temperature of the central region of the substrate that is in close contact with the spin coating chuck.

7. The spin coating apparatus according to claim 6, characterized in that, The heat exchange unit of the temperature control system is at least one semiconductor refrigeration chip; Alternatively, the heat exchange unit of the temperature control system includes a fluid channel disposed inside the uniform adhesive suction cup, and the fluid channel is connected to an external constant temperature circulating cooling device.

8. The spin coating apparatus according to any one of claims 6 or 7, characterized in that, The temperature control system also includes a temperature sensor, which is located on the upper surface of the adhesive suction cup near its supporting substrate.

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