Method and system for improving photoresist coating uniformity

Abstract

The invention provides a method and system for improving photoresist coating uniformity, and the method comprises the steps: determining a wafer, and carrying out the pretreatment to obtain a coated substrate; preparing a photoresist solution; enabling the gluing substrate to rotate and enabling the gluing nozzle to horizontally move along the diameter direction of the gluing substrate so as to spray a photoresist solution on the gluing substrate; drying the glued substrate on which the photoresist solution is sprayed; the spraying amount of the gluing nozzle is 10-50 [mu] l / s, and the solid content of the photoresist solution is 15%. Under the condition that other conditions are the same, when the spraying amount of the gluing nozzle is controlled to be 10-50 [mu] l / s and the solid content of the photoresist solution is configured to be 15%, the spraying amount is moderate, so that the collision speed of the photoresist liquid drops and the gluing substrate is moderate, at the moment, after the photoresist liquid drops collide with the gluing substrate, the liquid drops are in a balance stage, and the photoresist liquid drops are separated from the gluing substrate. And the situation that the whole liquid drop bounces or part of the liquid drop splashes is avoided, so that the photoresist coating uniformity is improved, and the photoresist waste is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductors, and in particular to a method for improving photoresist coating uniformity. Background Art

[0002] With the continuous development of wafer-level packaging, integrated circuits, and micro-electromechanical system devices, the application of photolithography technology has become more and more extensive, and it is known as a key technology to promote the development of the semiconductor industry. Gluing is an important part of the photolithography process. The thickness and uniformity of photoresist coating have a direct impact on the accuracy of subsequent photolithography patterns. Photoresist has high sensitivity, high adhesion, high resolution and good coating performance, and is widely used in the production of IC, TP, CF, LED and other products.

[0003] With the development of technology, the requirements of the existing technology for the thickness and uniformity of photoresist coating are getting higher and higher, making the requirements for the coating method more and more stringent. Most of the traditional photoresist coating methods use the centrifugal rotation method, taking a certain amount of photoresist solution and dripping it on the substrate, and under the centrifugal force of the rotating coating machine, the photoresist solution is evenly coated on the surface of the substrate. For example, take a certain amount of photoresist solution and drip it on the substrate, set the coating machine speed to 500-1000r / min, and rotate at a low speed for 5-10s, so that the low-speed rotation spreads the photoresist solution to the surface of the entire substrate; then set the coating machine speed to 1500-6000r / min, and rotate at a high speed for 10-120s, so that the high-speed rotation can throw out the excess photoresist; finally, let the coated substrate stay for a few minutes to allow the residual solvent in the photoresist to evaporate, and obtain a photoresist film with uniform thickness.

[0004] Although the above-mentioned centrifugal rotation method can obtain a photoresist film with uniform thickness, the thickness of the photoresist film is relatively thin and the thickness range adjustment is unstable; therefore, in the subsequent exposure process, it is easy to cause the photoresist film that does not need to be cleaned during the development process to be easily cleaned due to too long exposure time or misalignment between the mask and the photoresist film, and the expected clear and complete pattern cannot be photolithographed.

[0005] In addition, when the centrifugal rotation method is used for coating, the excess photoresist on the substrate is thrown out during the rotation of the coating machine, resulting in a problem of photoresist waste. Summary of the invention

[0006] The present invention aims to provide a method and system for improving the uniformity of photoresist coating, so as to solve the above-mentioned technical problems, improve the uniformity of photoresist coating and avoid photoresist waste.

[0007] In order to solve the above technical problems, the present invention provides a method for improving the uniformity of photoresist coating, comprising the following steps: Determine a wafer and perform pretreatment to obtain a glue-coated substrate; preparing a photoresist solution; Rotate the glue-coated substrate and move the glue-coated nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate; The coated substrate after spraying the photoresist solution is dried; wherein: The spraying amount of the glue coating nozzle is 10-50ul / s, and the solid content of the photoresist solution is 15%.

[0008] In the above scheme, experiments have shown that, under the same other conditions, when the injection volume of the coating nozzle is controlled to 10~50ul / s and the solid content of the photoresist solution is configured to 15%, the injection volume is moderate and the speed at which the photoresist droplets collide with the coating substrate is also moderate. At this time, after the photoresist droplets collide with the coating substrate, when the droplets are in the equilibrium stage (i.e., the stable state of the droplets), they do not have enough kinetic energy to be converted into potential energy, i.e., they cannot overcome the adsorption force of the coating substrate, avoiding the entire droplet from bouncing or part of the droplet from splashing, thereby improving the uniformity of photoresist coating and avoiding photoresist waste.

[0009] It should be noted that a solid content of the photoresist solution of 15% can obtain a thicker photoresist film layer, and there is no need to increase the spray volume of the coating nozzle during the spraying process, thereby avoiding the entire droplet from bouncing or part of the droplet from splashing, avoiding photoresist waste and improving the uniformity of photoresist coating.

[0010] Further, the step of determining a wafer and pre-processing it to obtain a glue-coated substrate is as follows: Determine a wafer; The wafer is treated with a sulfuric acid-hydrogen peroxide mixture, a sulfuric acid-ozone mixture or a hydrochloric acid-hydrogen peroxide mixture to obtain a glue-coated substrate; wherein: In the sulfuric acid and hydrogen peroxide mixture, the volume ratio of sulfuric acid to hydrogen peroxide is 1:1-50:1, and when the sulfuric acid and hydrogen peroxide mixture is used for the wafer processing, the temperature is 100° C.-180° C.; In the sulfuric acid-ozone mixture, the content of ozone is 1-50 ppm, and when the sulfuric acid-ozone mixture is used for the wafer processing, the temperature is 100° C.-180° C.; In the hydrochloric acid-hydrogen peroxide mixture, the volume ratio of hydrochloric acid, hydrogen peroxide and deionized water is 1:1:1~1:10:100. When the sulfuric acid-ozone mixture is used for the wafer processing, the temperature is 20°C~80°C.

[0011] In the above scheme, the wafer surface can be slightly oxidized by treating it with a sulfuric acid-hydrogen peroxide mixture, a sulfuric acid-ozone mixture, or a hydrochloric acid-hydrogen peroxide mixture before spraying the photoresist, thereby achieving the purpose of passivating the surface of the material, making the wafer surface more stable, and reducing the impact of air molecular pollutants. Experiments have shown that after pretreatment with acidic substances, the Ph value of the wafer surface is reduced, which is beneficial to the photoacid stability of the photoresist when spraying the photoresist, and can provide better photolithography control process capabilities in subsequent processes.

[0012] Furthermore, the wafer is treated with a sulfuric acid-hydrogen peroxide mixture, a sulfuric acid-ozone mixture or a hydrochloric acid-hydrogen peroxide mixture for 30 seconds to 30 minutes.

[0013] It should be noted that the wafer can also be pre-treated with anhydrous ethanol to isolate the wafer from the surrounding environment and prevent the wafer from adsorbing tiny particles in the surrounding environment.

[0014] Furthermore, the preparation of the photoresist solution is specifically as follows: AZ series photoresist, butanone and propylene glycol methyl ether acetate are mixed in a ratio of 1:1.5:0.5 to obtain a photoresist solution with a solid content of 15%.

[0015] The existing photoresist solution obtained by diluting AZ series photoresist with propylene glycol methyl ether acetate as a solvent is suitable for the spraying process, but the fluidity of the photoresist solution formed is too large, which easily affects the uniformity of the coating; and the viscosity of the photoresist solution obtained by diluting AZ series photoresist with butanone as a solvent is too large, which easily generates a photoresist film layer with high roughness. In the above scheme, the photoresist solution formed by mixing AZ series photoresist, butanone and propylene glycol methyl ether acetate in a ratio of 1:1.5:0.5 has a high volatility and can greatly reduce the movement of photoresist droplets, so that a more uniform photoresist film can be formed during the spraying process.

[0016] Furthermore, the step of rotating the glue-coated substrate and moving the glue-coated nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate is specifically as follows: determining a diameter of the rubber-coated substrate; Determine a half-normal distribution distance of the glue coating nozzle spraying the photoresist solution based on the diameter to satisfy D=2NT, where N is a positive integer, D is the diameter of the glue coating substrate, and T is the half-normal distribution distance; Taking the half-normal distribution distance T as the stepping distance of the glue coating nozzle, the glue coating substrate is rotated in coordination, so that when the glue coating nozzle moves horizontally along the diameter direction of the glue coating substrate, the unit time length of the photoresist solution sprayed on all areas on the glue coating substrate is the same; The unit time length is to divide the area of ​​the glue-coated substrate at the stepping distance into a plurality of units, and each unit is sprayed with the photoresist solution for a certain time length.

[0017] Experiments have shown that multiple sprayings with a half-normal distribution distance as a span are required to form a uniform and complete photoresist coating. In the above scheme, by controlling the stepping distance of the glue coating nozzle to be a half-normal distribution distance, the uniformity of the photoresist film layer formed by spraying can be ensured; the glue coating nozzle can achieve glue coating on the entire glue coating substrate by simply cooperating with the rotation of the glue coating substrate.

[0018] It should be noted that since the farther the glue-coated substrate is from the center of the circle, the larger the area that needs to be sprayed is, in order to ensure that each unit on the glue-coated substrate receives the sprayed photoresist solution for a consistent length of time, the residence time can be set according to the position of the glue-coated nozzle relative to the glue-coated substrate, that is, when the glue-coated nozzle is at the edge of the glue-coated substrate, its residence time is the longest, and when the glue-coated nozzle is at the center of the glue-coated substrate, its residence time is the shortest.

[0019] In the above scheme, setting D=2NT can ensure that the center of the glue-coated substrate can be directly below the glue-coating nozzle, ensuring the uniformity of the overall glue coating of the glue-coated substrate, and allowing most of the photoresist solution sprayed from the glue-coating nozzle to be accepted by the glue-coated substrate, thereby improving the uniformity of the photoresist coating and reducing the waste of photoresist solution.

[0020] Furthermore, the glue coating operation can be completed after the glue coating nozzle reaches the center of the glue coating substrate and sprays the photoresist solution; it may also be arranged that the glue coating nozzle starts spraying from the edge of one end of the glue coating substrate, and completes the glue coating operation after spraying the photoresist solution along the diameter to the edge of the other end of the glue coating substrate through the center of the circle. The residence time of the glue coating nozzle is different in the two glue coating methods, and it is only necessary to ensure that the unit time length of spraying the photoresist solution on all areas on the glue coating substrate is the same.

[0021] Furthermore, the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is determined based on the diameter to satisfy D=2NT, specifically: Based on the diameter, the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is adjusted by adjusting the distance between the glue coating nozzle and the glue coating substrate and the exit angle of the glue coating nozzle to satisfy D=2NT.

[0022] Furthermore, the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is adjusted, specifically: Establish an XY axis coordinate system on a blank coating; Using the glue coating nozzle to move along the X-axis on the blank coating and spray the photoresist solution once to obtain a normal distribution pattern, and taking the distance between the center and the edge of the normal distribution pattern as the half-normal distribution distance; By adjusting the distance between the glue coating nozzle and the glue coating substrate and the emission angle of the glue coating nozzle, the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle can be adjusted.

[0023] Furthermore, the angular velocity of the rubber-coated substrate is coordinated with the rotation satisfy: In the formula, Represents adhesion, which is related to the dynamic viscosity of the photoresist itself; It represents the average mass of photoresist droplets, which is related to the spray volume of the glue coating nozzle; It indicates the distance from the center of the photoresist droplet to the center of the coated substrate, that is, the horizontal distance from the center of the photoresist droplet to the rotation axis. When the angular velocity of the coated substrate meets the above, the photoresist particles will stably adhere to the coated substrate, avoiding uneven photoresist coating due to the centrifugal movement of the photoresist particles on the coated substrate.

[0024] The present invention also provides a system for improving the uniformity of photoresist coating, comprising: A pre-processing module is used to pre-process the determined wafer to obtain a glue-coated substrate; A solution configuration module, used to configure a photoresist solution with a solid content of 15%; A glue coating nozzle, used for spraying the photoresist solution on the glue coating substrate; A substrate turntable, used to carry the glue-coated substrate and to rotate; A control module is used to rotate the glue-coated substrate and move the glue-coating nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate; and at the same time, the spraying amount of the glue-coating nozzle is controlled to be 10-50ul / s; The drying module is used to dry the coated substrate after the photoresist solution is sprayed.

[0025] Furthermore, the control module is used to rotate the glue-coated substrate and move the glue-coated nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate, specifically: Based on the input diameter of the glue-coated substrate and the half-normal distribution distance of the glue-coated nozzle spraying the photoresist solution, the glue-coated nozzle is moved with the half-normal distribution distance as a step distance, and the glue-coated substrate is rotated in coordination, so that when the glue-coated nozzle moves horizontally along the diameter direction of the glue-coated substrate, the unit time length of the photoresist solution sprayed on all areas on the glue-coated substrate is the same; The unit time length is to divide the area of ​​the glue-coated substrate at the stepping distance into a plurality of units, and the time length for each unit to be sprayed with the photoresist solution; The diameter and the half-normal distribution distance satisfy D=2NT, wherein N is a positive integer, D is the diameter of the glue-coated substrate, and T is the half-normal distribution distance.

[0026] The system architecture provided by the above scheme is simple. When the injection volume of the coating nozzle is controlled to 10~50ul / s and the solid content of the photoresist solution is configured to 15%, the injection volume is moderate, so that the speed at which the photoresist droplets collide with the coating substrate is also moderate. At this time, after the photoresist droplets collide with the coating substrate, when the droplets are in the equilibrium stage (i.e., the stable state of the droplets), they do not have enough kinetic energy to be converted into potential energy, that is, they cannot overcome the adsorption force of the coating substrate, avoiding the entire droplet from bouncing or part of the droplet from splashing, thereby improving the uniformity of photoresist coating and avoiding photoresist waste.

[0027] The above system also sets D=2NT, thereby ensuring that the center of the coated substrate can be directly below the coating nozzle, ensuring the uniformity of the overall coating of the coated substrate, and allowing most of the photoresist solution sprayed by the coating nozzle to be accepted by the coated substrate, thereby improving the uniformity of the photoresist coating and reducing the waste of the photoresist solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic flow chart of a method for improving photoresist coating uniformity provided by one embodiment of the present invention; Figure 2 A schematic diagram of the spraying effect of the change in the spraying amount of the glue coating nozzle provided in one embodiment of the present invention; Figure 3 A schematic diagram of the spraying effect of a photoresist solution with different solid contents provided by an embodiment of the present invention; Figure 4 A schematic diagram of the effect of spraying a photoresist solution once along the X-axis on a blank coating provided by an embodiment of the present invention; Figure 5 An embodiment of the present invention provides Figure 4 Schematic diagram of the effect after the second photoresist solution spraying along the X-axis on the edge of the pattern; Figure 6 An embodiment of the present invention provides Figure 5Schematic diagram of the effect after the third photoresist solution spraying along the X-axis in the middle of the pattern; Figure 7 A schematic diagram of the spraying position of a glue coating nozzle provided in one embodiment of the present invention; Figure 8 A schematic diagram of a system architecture for improving photoresist coating uniformity provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figure 1 This embodiment provides a method for improving the uniformity of photoresist coating, comprising the following steps: Step S1: determine a wafer and perform pretreatment to obtain a glue-coated substrate; Step S2: preparing a photoresist solution; Step S3: rotating the glue-coated substrate and moving the glue-coating nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate; Step S4: drying the coated substrate after spraying the photoresist solution; wherein: The spraying amount of the glue coating nozzle is 10-50ul / s, and the solid content of the photoresist solution is 15%.

[0031] In this embodiment, experiments have shown that, under the same other conditions, when the spray volume of the coating nozzle is controlled to 10~50ul / s and the solid content of the photoresist solution is configured to 15%, the spray volume is moderate and the speed at which the photoresist droplets collide with the coating substrate is also moderate. At this time, after the photoresist droplets collide with the coating substrate, when the droplets are in the equilibrium stage (i.e., the stable state of the droplets), they do not have enough kinetic energy to be converted into potential energy, i.e., they cannot overcome the adsorption force of the coating substrate, avoiding the entire droplet from bouncing or part of the droplet from splashing, thereby improving the uniformity of photoresist coating and avoiding photoresist waste.

[0032] It should be noted that a solid content of the photoresist solution of 15% can obtain a thicker photoresist film layer, and there is no need to increase the spray volume of the coating nozzle during the spraying process, thereby avoiding the entire droplet from bouncing or part of the droplet from splashing, avoiding photoresist waste and improving the uniformity of photoresist coating.

[0033] In order to further illustrate the technical effect of the present invention, this embodiment is verified by the control variable method. Specifically, the photoresist solution used in the experiment of this embodiment is the same, the spray angle of the nozzle is the same, the number of spraying steps is the same, and the distance from the coating nozzle to the coating substrate is also the same. In order to ensure the uniformity of the photoresist coating, the angular velocity of the coating substrate and the moving speed of the coating nozzle are the same in the corresponding number of steps between each experiment, that is, the only variable is the spray volume of the coating nozzle, and its range of variation is 10~110ul / s. Two experiments were carried out under the same conditions. The comparison of the experimental data and the ideal data can be seen in Figure 2 As shown. Figure 2 It can be seen that the data obtained from the experiment when the injection amount is in the range of 10~50ul / s is very close to the ideal value. When the injection amount is 60~110ul / s, both experiments deviate from the ideal value. The experimental surface shows that as the injection amount increases, the injection speed of the glue coating nozzle will also increase, and then the collision speed of the photoresist droplet and the glue coating substrate will increase, and then the photoresist droplet will have enough kinetic energy to convert into potential energy in the equilibrium stage after colliding with the glue coating substrate, and finally overcome the adsorption force of the glue coating substrate to make the entire photoresist droplet bounce or part of the droplet splash, so its experimental data will obviously deviate from the ideal value. Therefore, this embodiment can fully illustrate that when the injection amount is 10~50ul / s, the photoresist droplet will not have enough kinetic energy to convert into potential energy in the equilibrium stage (i.e., the droplet stable state) after colliding with the glue coating substrate, that is, it is impossible to overcome the adsorption force of the glue coating substrate, and avoid the situation that the entire droplet bounces or part of the droplet splashes, thereby improving the photoresist coating uniformity and avoiding photoresist waste.

[0034] In order to further illustrate the technical effect of the present invention, this embodiment is verified by the control variable method. Specifically, the nozzles used in the experiment of this embodiment have the same spray angle, the same number of spraying steps, and the same distance from the coating nozzle to the coating substrate. In order to ensure the uniformity of the photoresist coating, the angular velocity of the coating substrate and the moving speed of the coating nozzle are the same in the corresponding number of steps between each experiment, that is, the only variable is the solid content of the photoresist, which is 4 groups of photoresist solutions of 5%, 7%, 10% and 15% respectively. Four experiments were carried out under the same conditions. The comparison of the experimental data and the ideal data can be seen in Figure 3 As shown. Figure 3It can be seen that the thickness of the photoresist increases with the increase of solid content and spraying amount. The results obtained by spraying photoresist solutions with solid content of 5% and 7% show that the thickness of the photoresist does not change much with the gradual increase of the spraying amount. This is because the fluidity of the photoresist is large when the solid content is low, so it is difficult to form a thicker film layer. When the solid content of the photoresist solution is 15%, a thicker photoresist film layer can be obtained. During the spraying process, there is no need to increase the spraying amount of the coating nozzle, thereby avoiding the situation where the entire droplet bounces or part of the droplet splashes, avoiding photoresist waste and improving the uniformity of photoresist coating.

[0035] Further, the method of determining a wafer and pre-treating it to obtain a coated substrate is specifically as follows: determining a wafer; treating the wafer with a sulfuric acid-hydrogen peroxide mixture, a sulfuric acid-ozone mixture or a hydrochloric acid-hydrogen peroxide mixture to obtain a coated substrate; wherein: in the sulfuric acid-hydrogen peroxide mixture, the volume ratio of sulfuric acid to hydrogen peroxide is 1:1~50:1, and when the sulfuric acid-hydrogen peroxide mixture is used for the wafer treatment, the temperature is 100°C~180°C; in the sulfuric acid-ozone mixture, the ozone content is 1~50ppm, and when the sulfuric acid-ozone mixture is used for the wafer treatment, the temperature is 100°C~180°C; in the hydrochloric acid-hydrogen peroxide mixture, the volume ratio of hydrochloric acid, hydrogen peroxide and deionized water is 1:1:1~1:10:100, and when the sulfuric acid-ozone mixture is used for the wafer treatment, the temperature is 20°C~80°C.

[0036] In this embodiment, the wafer is treated with a sulfuric acid-hydrogen peroxide mixture, a sulfuric acid-ozone mixture, or a hydrochloric acid-hydrogen peroxide mixture before the photoresist is sprayed, so that the surface of the wafer can be slightly oxidized to achieve the purpose of passivating the surface of the material, making the surface of the wafer more stable and reducing the influence of air molecular pollutants. Experiments have shown that after pretreatment with an acidic substance, the Ph value of the wafer surface is reduced, which is beneficial to the photoacid stability of the photoresist when spraying the photoresist, and can provide better photolithography control process capabilities in subsequent processes.

[0037] Furthermore, the wafer is treated with a sulfuric acid-hydrogen peroxide mixture, a sulfuric acid-ozone mixture or a hydrochloric acid-hydrogen peroxide mixture for 30 seconds to 30 minutes.

[0038] It should be noted that the wafer can also be pre-treated with anhydrous ethanol to isolate the wafer from the surrounding environment and prevent the wafer from adsorbing tiny particles in the surrounding environment.

[0039] Furthermore, the preparation of the photoresist solution is specifically as follows: AZ series photoresist, butanone and propylene glycol methyl ether acetate are mixed in a ratio of 1:1.5:0.5 to obtain a photoresist solution with a solid content of 15%.

[0040] The existing photoresist solution obtained by diluting AZ series photoresist with propylene glycol methyl ether acetate as a solvent is suitable for the spraying process, but the fluidity of the photoresist solution formed is too large, which easily affects the uniformity of the coating; and the viscosity of the photoresist solution obtained by diluting AZ series photoresist with butanone as a solvent is too large, which easily generates a photoresist film layer with high roughness. In the above scheme, the photoresist solution formed by mixing AZ series photoresist, butanone and propylene glycol methyl ether acetate in a ratio of 1:1.5:0.5 has a high volatility and can greatly reduce the movement of photoresist droplets, so that a more uniform photoresist film can be formed during the spraying process.

[0041] Furthermore, the step of rotating the glue-coated substrate and moving the glue-coating nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate is specifically as follows: determining the diameter of the glue-coated substrate; determining a half-normal distribution distance for the glue-coating nozzle to spray the photoresist solution based on the diameter to satisfy D=2NT, wherein N is a positive integer, D is the diameter of the glue-coated substrate, and T is the half-normal distribution distance; taking the half-normal distribution distance T as the stepping distance of the glue-coating nozzle, the glue-coated substrate is rotated in coordination, so that when the glue-coating nozzle moves horizontally along the diameter direction of the glue-coated substrate, the unit time length for spraying the photoresist solution on all areas of the glue-coated substrate is the same; the unit time length is to divide the area of ​​the glue-coated substrate at the stepping distance into a plurality of units, and each unit is sprayed with the photoresist solution for a certain time length.

[0042] In this embodiment, by controlling the stepping distance of the glue coating nozzle to be a semi-normal distribution distance, the uniformity of the photoresist film layer formed by spraying can be ensured; the glue coating nozzle can achieve glue coating on the entire glue coating substrate only by coordinating the rotation of the glue coating substrate.

[0043] In this embodiment, since the farther the glue-coated substrate is from the center of the circle, the larger the area that needs to be sprayed is, in order to ensure that each unit on the glue-coated substrate receives the sprayed photoresist solution for a consistent length of time, the residence time can be set according to the position of the glue-coated nozzle relative to the glue-coated substrate, that is, when the glue-coated nozzle is at the edge of the glue-coated substrate, its residence time is the longest, and when the glue-coated nozzle is at the center of the glue-coated substrate, its residence time is the shortest.

[0044] In this embodiment, setting D=2NT can ensure that the center of the glue-coated substrate can be directly below the glue-coating nozzle, ensuring the uniformity of the overall glue coating of the glue-coated substrate, and allowing most of the photoresist solution sprayed from the glue-coating nozzle to be accepted by the glue-coated substrate, thereby improving the uniformity of the photoresist coating and reducing the waste of photoresist solution.

[0045] Furthermore, the glue coating operation can be completed after the glue coating nozzle reaches the center of the glue coating substrate and sprays the photoresist solution; it may also be arranged that the glue coating nozzle starts spraying from the edge of one end of the glue coating substrate, and completes the glue coating operation after spraying the photoresist solution along the diameter to the edge of the other end of the glue coating substrate through the center of the circle. The residence time of the glue coating nozzle is different in the two glue coating methods, and it is only necessary to ensure that the unit time length of spraying the photoresist solution on all areas on the glue coating substrate is the same.

[0046] Furthermore, the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is determined based on the diameter to satisfy D=2NT, specifically: Based on the diameter, the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is adjusted by adjusting the distance between the glue coating nozzle and the glue coating substrate and the exit angle of the glue coating nozzle to satisfy D=2NT.

[0047] Furthermore, the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is adjusted, specifically: an XY axis coordinate system is established on a blank coating; the glue coating nozzle is moved along the X axis on the blank coating and the photoresist solution is sprayed once to obtain a normal distribution pattern, and the distance between the center and the edge of the normal distribution pattern is used as the half-normal distribution distance; the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is adjusted by adjusting the distance between the glue coating nozzle and the glue coating substrate and the exit angle of the glue coating nozzle.

[0048] Experiments have shown that multiple sprayings with a half-normal distribution distance as the span are required to form a uniform and complete photoresist coating. For details, see Figure 4~Figure 6 First, an XY axis coordinate system is established on the blank coating, and then the coating nozzle is moved along the X axis and the photoresist solution is sprayed once. At this time, the following can be obtained: Figure 4 The pattern shown in FIG. 1 is shown in FIG. 2 . Obviously, the obtained pattern presents a normal distribution. Here, the photoresist solution is sprayed downward along the Y-axis and along the X-axis at the edge of the first pattern. At this time, the following can be obtained: Figure 5 The pattern shown. Obviously, Figure 5 The entire middle part of the pattern presented is almost not covered with photoresist, indicating that a uniform photoresist film layer cannot be obtained by spraying with a normal distribution length as a period during the entire spraying process.

[0049] Therefore, in Figure 5 Based on the pattern, the third spraying is performed in the middle part, and the final pattern is as follows Figure 6 shown. Figure 6It can be clearly seen that after three sprayings, the middle part of the entire spraying area obtains the best glue coating effect. Therefore, by controlling the stepping distance of the glue coating nozzle to be a semi-normal distribution distance, the uniformity of the photoresist film layer formed by spraying can be ensured; the glue coating nozzle can achieve glue coating on the entire glue coating substrate by simply coordinating the rotation of the glue coating substrate.

[0050] In order to further illustrate the technical features of the present invention, this embodiment Figure 7 From Figure 7 It can be seen that the stepping distance of the coating nozzle is a half-normal distribution distance, which can ensure the uniformity of the photoresist film layer formed by spraying. And D=2NT can ensure that the center of the coating substrate is directly below the stepping path of the coating nozzle, ensuring the uniformity of the overall coating of the coating substrate, so that most of the photoresist solution sprayed by the coating nozzle can be accepted by the coating substrate, improving the uniformity of the photoresist coating while reducing the waste of the photoresist solution.

[0051] Furthermore, the angular velocity of the rubber-coated substrate is coordinated with the rotation satisfy: In the formula, Represents adhesion, which is related to the dynamic viscosity of the photoresist itself; It represents the average mass of photoresist droplets, which is related to the spray volume of the glue coating nozzle; It indicates the distance from the center of the photoresist droplet to the center of the coated substrate, that is, the horizontal distance from the center of the photoresist droplet to the rotation axis. When the angular velocity of the coated substrate meets the above, the photoresist particles will stably adhere to the coated substrate, avoiding uneven photoresist coating due to the centrifugal movement of the photoresist particles on the coated substrate.

[0052] See also Figure 8 This embodiment also provides a system for improving the uniformity of photoresist coating, including: A pre-processing module is used to pre-process the determined wafer to obtain a glue-coated substrate; A solution configuration module, used to configure a photoresist solution with a solid content of 15%; A glue coating nozzle, used for spraying the photoresist solution on the glue coating substrate; A substrate turntable, used to carry the glue-coated substrate and to rotate; A control module is used to rotate the glue-coated substrate and move the glue-coating nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate; and at the same time, the spraying amount of the glue-coating nozzle is controlled to be 10-50ul / s; The drying module is used to dry the coated substrate after the photoresist solution is sprayed.

[0053] Furthermore, the control module is used to rotate the glue-coated substrate and move the glue-coated nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate, specifically: Based on the input diameter of the glue-coated substrate and the half-normal distribution distance of the glue-coated nozzle spraying the photoresist solution, the glue-coated nozzle is moved with the half-normal distribution distance as a step distance, and the glue-coated substrate is rotated in coordination, so that when the glue-coated nozzle moves horizontally along the diameter direction of the glue-coated substrate, the unit time length of the photoresist solution sprayed on all areas on the glue-coated substrate is the same; The unit time length is to divide the area of ​​the glue-coated substrate at the stepping distance into a plurality of units, and the time length for each unit to be sprayed with the photoresist solution; The diameter and the half-normal distribution distance satisfy D=2NT, wherein N is a positive integer, D is the diameter of the glue-coated substrate, and T is the half-normal distribution distance.

[0054] The system architecture provided in this embodiment is simple. When the spray volume of the coating nozzle is controlled to 10~50ul / s and the solid content of the photoresist solution is configured to 15%, the spray volume is moderate and the speed at which the photoresist droplets collide with the coating substrate is also moderate. At this time, after the photoresist droplets collide with the coating substrate, when the droplets are in the equilibrium stage (i.e., the stable state of the droplets), they do not have enough kinetic energy to be converted into potential energy, i.e., they cannot overcome the adsorption force of the coating substrate, avoiding the entire droplet from bouncing or part of the droplet from splashing, thereby improving the uniformity of photoresist coating and avoiding photoresist waste.

[0055] The above system also sets D=2NT, thereby ensuring that the center of the coated substrate can be directly below the coating nozzle, ensuring the uniformity of the overall coating of the coated substrate, and allowing most of the photoresist solution sprayed by the coating nozzle to be accepted by the coated substrate, thereby improving the uniformity of the photoresist coating and reducing the waste of the photoresist solution.

[0056] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for improving the uniformity of photoresist coating, characterized in that: The following steps are involved: Determine a wafer and perform pretreatment to obtain a glue-coated substrate; preparing a photoresist solution; Rotate the glue-coated substrate and move the glue-coated nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate; The coated substrate after spraying the photoresist solution is dried; wherein: The spraying amount of the glue coating nozzle is 10-50ul / s, and the solid content of the photoresist solution is 15%.

2. A method for improving photoresist coating uniformity according to claim 1, characterized in that: The step of determining a wafer and performing pretreatment to obtain a glue-coated substrate is as follows: Determine a wafer; The wafer is treated with a sulfuric acid-hydrogen peroxide mixture, a sulfuric acid-ozone mixture or a hydrochloric acid-hydrogen peroxide mixture to obtain a glue-coated substrate; wherein: In the sulfuric acid and hydrogen peroxide mixture, the volume ratio of sulfuric acid to hydrogen peroxide is 1:1-50:1, and when the sulfuric acid and hydrogen peroxide mixture is used for the wafer processing, the temperature is 100° C.-180° C.; In the sulfuric acid-ozone mixture, the content of ozone is 1-50 ppm, and when the sulfuric acid-ozone mixture is used for the wafer processing, the temperature is 100° C.-180° C.; In the hydrochloric acid-hydrogen peroxide mixture, the volume ratio of hydrochloric acid, hydrogen peroxide and deionized water is 1:1:1~1:10:

100. When the sulfuric acid-ozone mixture is used for the wafer processing, the temperature is 20°C~80°C.

3. A method for improving photoresist coating uniformity according to claim 2, characterized in that: The wafer is treated with a sulfuric acid-hydrogen peroxide mixture, a sulfuric acid-ozone mixture or a hydrochloric acid-hydrogen peroxide mixture for 30 seconds to 30 minutes.

4. A method for improving photoresist coating uniformity according to claim 1, characterized in that: The photoresist solution is specifically configured as follows: AZ series photoresist, butanone and propylene glycol methyl ether acetate were mixed in a ratio of 1:1.5:0.5 to obtain a photoresist solution with a solid content of 15%.

5. A method for improving photoresist coating uniformity according to any one of claims 1 to 4, characterized in that: The step of rotating the glue-coated substrate and moving the glue-coated nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate is specifically as follows: determining a diameter of the rubber-coated substrate; Determine a half-normal distribution distance of the glue coating nozzle spraying the photoresist solution based on the diameter to satisfy D=2NT, where N is a positive integer, D is the diameter of the glue coating substrate, and T is the half-normal distribution distance; Taking the half-normal distribution distance T as the stepping distance of the glue coating nozzle, the glue coating substrate is rotated in coordination, so that when the glue coating nozzle moves horizontally along the diameter direction of the glue coating substrate, the unit time length of the photoresist solution sprayed on all areas on the glue coating substrate is the same; The unit time length is to divide the area of ​​the glue-coated substrate at the stepping distance into a plurality of units, and each unit is sprayed with the photoresist solution for a certain time length.

6. A method for improving photoresist coating uniformity according to claim 5, characterized in that: The half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is determined based on the diameter to satisfy D=2NT, specifically: Based on the diameter, the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is adjusted by adjusting the distance between the glue coating nozzle and the glue coating substrate and the exit angle of the glue coating nozzle to satisfy D=2NT.

7. A method for improving photoresist coating uniformity according to claim 6, characterized in that: The half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle is adjusted, specifically: Establish an XY axis coordinate system on a blank coating; Using the glue coating nozzle to move along the X-axis on the blank coating and spray the photoresist solution once to obtain a normal distribution pattern, and taking the distance between the center and the edge of the normal distribution pattern as the half-normal distribution distance; By adjusting the distance between the glue coating nozzle and the glue coating substrate and the emission angle of the glue coating nozzle, the half-normal distribution distance of the photoresist solution sprayed by the glue coating nozzle can be adjusted.

8. The method for improving the uniformity of photoresist coating according to claim 5, characterized in that: The angular velocity of the rubber-coated substrate rotation satisfy: In the formula, Represents adhesion, which is related to the dynamic viscosity of the photoresist itself; It represents the average mass of photoresist droplets, which is related to the spray volume of the glue coating nozzle; It represents the distance from the center of the photoresist droplet to the center of the coated substrate, that is, the horizontal distance from the center of the photoresist droplet to the rotation axis.

9. A system for improving uniformity of photoresist coating, characterized in that: include: A pre-processing module is used to pre-process the determined wafer to obtain a glue-coated substrate; A solution configuration module, used to configure a photoresist solution with a solid content of 15%; A glue coating nozzle, used for spraying the photoresist solution on the glue coating substrate; A substrate turntable, used to carry the glue-coated substrate and to rotate; A control module is used to rotate the glue-coated substrate and move the glue-coating nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate; and at the same time, the spraying amount of the glue-coating nozzle is controlled to be 10-50ul / s; The drying module is used to dry the coated substrate after the photoresist solution is sprayed.

10. A system for improving uniformity of photoresist coating according to claim 9, characterized in that: The control module is used to rotate the glue-coated substrate and move the glue-coated nozzle horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate, specifically: Based on the input diameter of the glue-coated substrate and the half-normal distribution distance of the glue-coated nozzle spraying the photoresist solution, the glue-coated nozzle is moved with the half-normal distribution distance as a step distance, and the glue-coated substrate is rotated in coordination, so that when the glue-coated nozzle moves horizontally along the diameter direction of the glue-coated substrate, the unit time length of the photoresist solution sprayed on all areas on the glue-coated substrate is the same; The unit time length is to divide the coated substrate into a number of units, and the time length for each unit to be sprayed with the photoresist solution; The diameter and the half-normal distribution distance satisfy D=2NT, wherein N is a positive integer, D is the diameter of the glue-coated substrate, and T is the half-normal distribution distance.

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