A method and system for improving the coating uniformity of photoresist

Abstract

The present invention provides a method and a system for improving the coating uniformity of photoresist. The method includes determining a wafer and performing pre-treatment to obtain a coating substrate; configuring a photoresist solution; rotating the coating substrate and horizontally moving the photoresist nozzle along the diameter direction of the coating substrate to spray the photoresist solution onto the coating substrate; drying the coating substrate after spraying the photoresist solution; the spraying amount of the photoresist nozzle is 10-50 ul / 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 photoresist nozzle is controlled to be 10-50 ul / s and the solid content of the photoresist solution is configured to be 15%, the spraying amount is appropriate, so that the collision speed of the photoresist droplets with the coating substrate is also appropriate. At this time, the photoresist droplets are in the equilibrium stage after colliding with the coating substrate, avoiding the situation that the whole droplet bounces or part of the droplet splashes, thereby improving the coating uniformity of the photoresist and avoiding the waste of photoresist.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for improving the coating uniformity of photoresist. Background Art

[0002] With the continuous development of wafer-level packaging, integrated circuits, and microelectromechanical system devices, the application of lithography technology is becoming more and more extensive, and it is called a key technology to promote the development of the semiconductor industry. And spin coating is an important link in the lithography process. The thickness and uniformity of the photoresist coating have a direct impact on the accuracy of the subsequent lithography pattern. Photoresist has high sensitivity, high adhesion, high resolution, and good coating performance, and is widely used in the production of products such as IC, TP, CF, and LED.

[0003] With the development of technology, the requirements for the coating thickness and uniformity of photoresist in the prior art are also 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. A certain amount of photoresist solution is dropped on the substrate, and under the action of the centrifugal force of the spin coater rotation, the photoresist solution is uniformly coated on the surface of the substrate. For example, a certain amount of photoresist solution is dropped on the substrate, the rotation speed of the spin coater is set to 500 - 1000 r / min, and it rotates at a low speed for 5 - 10 s. In this way, the low-speed rotation spreads the photoresist solution over the entire surface of the substrate; then the rotation speed of the spin coater is set to 1500 - 6000 r / min, and it rotates at a high speed for 10 - 120 s. In this way, the excess photoresist is thrown out; finally, the substrate with the coated photoresist is left for several minutes to volatilize the residual solvent in the photoresist, and a photoresist film with uniform thickness is obtained.

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

[0005] In addition, when using the centrifugal rotation method for spin coating, the excess photoresist on the substrate is thrown out during the rotation of the spin coater, resulting in the problem of photoresist waste. Summary of the Invention

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

[0007] To solve the above technical problems, the present invention provides a method for improving the coating uniformity of photoresist, including the following steps:

[0008] Determine a wafer and perform pre-treatment to obtain a glue-coated substrate;

[0009] Prepare a photoresist solution;

[0010] Rotate the glue-coated substrate and horizontally move the glue-spraying nozzle along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate;

[0011] Dry the glue-coated substrate after spraying the photoresist solution; wherein:

[0012] The spraying amount of the glue-spraying nozzle is 10 - 50 μl / s, and the solid content of the photoresist solution is 15%.

[0013] In the above solution, experiments have shown that under the same other conditions, when the spraying amount of the glue-spraying nozzle is controlled to be 10 - 50 μl / 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 droplets with the glue-coated substrate is also moderate. At this time, when the photoresist droplets collide with the glue-coated substrate and 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 glue-coated substrate, avoiding the situation of the entire droplet bouncing up or partial droplet splashing, thereby improving the uniformity of photoresist coating and avoiding waste of photoresist.

[0014] It should be noted that when the solid content of the photoresist solution is 15%, a relatively thick photoresist film layer can be obtained. During the spraying process, it is not necessary to increase the spraying amount of the glue-spraying nozzle, thereby avoiding the situation of the entire droplet bouncing up or partial droplet splashing, avoiding waste of photoresist and improving the uniformity of photoresist coating.

[0015] Further, the determination of a wafer and performing pre-treatment to obtain a glue-coated substrate is specifically as follows:

[0016] Determine a wafer;

[0017] Treat the wafer 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:

[0018] In the sulfuric acid-hydrogen peroxide mixture, the volume ratio of sulfuric acid to hydrogen peroxide is 1:1 - 50:1. When the sulfuric acid-hydrogen peroxide mixture is used for wafer treatment, the temperature is 100°C - 180°C;

[0019] In the sulfuric acid-ozone mixture, the ozone content is 1 - 50 ppm. When the sulfuric acid-ozone mixture is used for wafer treatment, the temperature is 100°C - 180°C;

[0020] In the hydrochloric acid and hydrogen peroxide mixture, the volume ratio of hydrochloric acid, hydrogen peroxide and deionized water is 1:1:1 to 1:10:100. When the sulfuric acid and ozone mixture is used for the wafer treatment, the temperature is 20°C to 80°C.

[0021] In the above solution, before spraying photoresist on the wafer, treatment with a sulfuric acid and hydrogen peroxide mixture, a sulfuric acid and ozone mixture, or a hydrochloric acid and hydrogen peroxide mixture can micro-oxidize the wafer surface, achieving the purpose of passivating the material surface, making the wafer surface more stable and reducing the influence of air molecular pollutants. Experiments have shown that after pretreatment with acidic substances, the pH value of the wafer surface decreases, which is beneficial to the photoacid stability of the photoresist when spraying the photoresist, and can provide better lithography control process capabilities in subsequent processes.

[0022] Furthermore, the duration of treating the wafer with the sulfuric acid and hydrogen peroxide mixture, the sulfuric acid and ozone mixture, or the hydrochloric acid and hydrogen peroxide mixture is 30s to 30min.

[0023] It should be noted that the wafer can also be pretreated with anhydrous ethanol to isolate the wafer from the surrounding environment and avoid the adsorption of fine particles in the surrounding environment by the wafer.

[0024] Furthermore, the preparation of the photoresist solution is specifically as follows: Mix AZ series photoresist, methyl ethyl ketone, and propylene glycol monomethyl ether acetate in a ratio of 1:1.5:0.5 to obtain a photoresist solution with a solid content of 15%.

[0025] Although the existing photoresist solution obtained by diluting AZ series photoresist with propylene glycol monomethyl ether acetate is suitable for the spraying process, the formed photoresist solution has too high fluidity and is likely to affect the uniformity of the coating; while the photoresist solution obtained by diluting AZ series photoresist with methyl ethyl ketone has too high viscosity and is likely to generate a photoresist film layer with high roughness. In the above solution, the photoresist solution formed by mixing AZ series photoresist, methyl ethyl ketone, and propylene glycol monomethyl ether acetate in a ratio of 1:1.5:0.5 has a high evaporation rate and can greatly reduce the movement of photoresist droplets, so that a more uniform photoresist film can be formed during the spraying process.

[0026] Furthermore, the step of rotating the coating substrate and horizontally moving the coating nozzle along the diameter direction of the coating substrate to spray the photoresist solution on the coating substrate is specifically as follows:

[0027] Determine the diameter of the coating substrate;

[0028] Based on the diameter, determine the semi-normal distribution distance for the coating nozzle to spray the photoresist solution to satisfy D = 2NT, where N is a positive integer, D is the diameter of the coating substrate, and T is the semi-normal distribution distance;

[0029] Taking the semi - normal distribution distance T as the step distance of the glue - applying nozzle, and making the glue - applying substrate rotate cooperatively, so that when the glue - applying nozzle moves horizontally along the diameter direction of the glue - applying substrate, the unit time for all areas on the glue - applying substrate to be sprayed with the photoresist solution is the same;

[0030] The unit time is to divide the area of the glue - applying substrate at the step distance into several units, and the time for each unit to receive the spraying of the photoresist solution.

[0031] Experiments have shown that to form a uniform and complete photoresist coating, it is necessary to perform multiple sprays with a semi - normal distribution distance as the span. In the above - mentioned scheme, by controlling the step distance of the glue - applying nozzle to be the semi - normal distribution distance, the uniformity of the photoresist film layer formed by spraying can be ensured; only by cooperating with the rotation of the glue - applying substrate, the glue - applying nozzle can achieve glue - applying to the entire glue - applying substrate.

[0032] It should be noted that since the farther the glue - applying substrate is from the center of the circle, the larger the area to be sprayed. To ensure that the time for each unit on the glue - applying substrate to receive the spraying of the photoresist solution is the same, the residence time can be set according to the position of the glue - applying nozzle relative to the glue - applying substrate, that is, when the glue - applying nozzle is at the edge of the glue - applying substrate, its residence time is the longest, and when the glue - applying nozzle is at the center of the glue - applying substrate, its residence time is the shortest.

[0033] In the above - mentioned scheme, making D = 2NT can ensure that the center of the glue - applying substrate can be directly below the glue - applying nozzle, ensuring the uniformity of the overall glue - applying of the glue - applying substrate, so that most of the photoresist solution sprayed by the glue - applying nozzle can be received by the glue - applying substrate, reducing the waste of the photoresist solution while improving the uniformity of photoresist glue - applying.

[0034] Furthermore, the glue - applying operation can be completed after the glue - applying nozzle reaches the center of the glue - applying substrate and finishes spraying the photoresist solution; it can also be set that the glue - applying nozzle starts spraying from one - end edge of the glue - applying substrate, passes through the center of the circle along the diameter, and finishes spraying the photoresist solution at the other - end edge of the glue - applying substrate before completing the glue - applying operation. The residence times of the glue - applying nozzle in the two glue - applying methods are different, and only need to ensure that the unit time for all areas on the glue - applying substrate to be sprayed with the photoresist solution is the same.

[0035] Furthermore, determining the semi - normal distribution distance for the glue - applying nozzle to spray the photoresist solution based on the diameter to satisfy D = 2NT, specifically:

[0036] Based on the diameter, by adjusting the distance between the glue - applying nozzle and the glue - applying substrate and the exit angle of the glue - applying nozzle, the semi - normal distribution distance for the glue - applying nozzle to spray the photoresist solution is adjusted to satisfy D = 2NT.

[0037] Further, the adjustment of the semi-normal distribution distance of the photoresist solution sprayed by the glue application nozzle is specifically as follows:

[0038] Establish an X-Y axis coordinate system on a blank coating;

[0039] Use the glue application nozzle to move along the X-axis on the blank coating and perform a first spraying of the photoresist solution to obtain a normal distribution pattern, and take the distance between the center and the edge of the normal distribution pattern as the semi-normal distribution distance;

[0040] By adjusting the distance between the glue application nozzle and the glue application substrate and the ejection angle of the glue application nozzle, the adjustment of the semi-normal distribution distance of the photoresist solution sprayed by the glue application nozzle is achieved.

[0041] Further, the angular velocity of the rotation of the glue application substrate Satisfies:

[0042]

[0043] In the formula, Represents the adhesion force, which is related to the dynamic viscosity of the photoresist itself; Represents the average mass of the photoresist droplets, which is related to the ejection volume of the glue application nozzle; Represents the distance from the center of the photoresist droplet to the center of the glue application substrate, that is, the horizontal distance from the center of the photoresist droplet to the rotating shaft. When the angular velocity of the rotation of the glue application substrate satisfies the above, the photoresist particles will stably adhere to the glue application substrate, avoiding uneven photoresist coating caused by the centrifugal movement of the photoresist particles on the glue application substrate.

[0044] The present invention also proposes a system for improving the uniformity of photoresist coating, including:

[0045] A pretreatment module for pretreating the determined wafer to obtain a glue application substrate;

[0046] A solution configuration module for configuring a photoresist solution with a solid content of 15%;

[0047] A glue application nozzle for spraying the photoresist solution on the glue application substrate;

[0048] A substrate turntable for carrying the glue application substrate and being rotatable;

[0049] A control module for rotating the glue application substrate and horizontally moving the glue application nozzle along the diameter direction of the glue application substrate to spray the photoresist solution on the glue application substrate; and simultaneously controlling the ejection volume of the glue application nozzle to be 10 - 50 ul / s;

[0050] A drying module for drying the coated substrate after spraying the photoresist solution.

[0051] Furthermore, the control module is configured to rotate the coated substrate and horizontally move the coating nozzle along the diameter direction of the coated substrate to spray the photoresist solution on the coated substrate. Specifically:

[0052] Based on the input diameter of the coated substrate and the semi - normal distribution distance at which the coating nozzle sprays the photoresist solution, the coating nozzle is made to move with the semi - normal distribution distance as the step distance, and the coated substrate is made to rotate accordingly, so that when the coating nozzle moves horizontally along the diameter direction of the coated substrate, the unit time for spraying the photoresist solution on all areas of the coated substrate is the same;

[0053] The unit time is to divide the area of the coated substrate at the step distance into several units, and the time for each unit to receive the sprayed photoresist solution;

[0054] The diameter and the semi - normal distribution distance satisfy D = 2NT, where N is a positive integer, D is the diameter of the coated substrate, and T is the semi - normal distribution distance.

[0055] The system architecture provided by the above - mentioned solution is simple. When the spraying amount of the coating nozzle is controlled to be 10 - 50 ul / s and the solid content of the photoresist solution is configured to be 15%, the spraying amount is moderate, so that the speed of the photoresist droplets colliding with the coated substrate is also moderate. At this time, when the photoresist droplets collide with the coated substrate and 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 coated substrate, avoiding the situation of the whole droplet bouncing up or partial droplet splashing, thereby improving the uniformity of photoresist coating and avoiding waste of photoresist.

[0056] The above - mentioned system also makes 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, making most of the photoresist solution sprayed by the coating nozzle be received by the coated substrate, improving the uniformity of photoresist coating while reducing the waste of photoresist solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic flow chart of the steps of a method for improving the uniformity of photoresist coating provided by an embodiment of the present invention;

[0058] Figure 2 It is a schematic diagram of the spraying effect of the change in the spraying amount of the coating nozzle provided by an embodiment of the present invention;

[0059] Figure 3Schematic diagram of spraying effect under different solid contents of photoresist solution provided by an embodiment of the present invention;

[0060] Figure 4 Schematic diagram of the effect after spraying the photoresist solution once along the X-axis on a blank coating provided by an embodiment of the present invention;

[0061] Figure 5 provided by an embodiment of the present invention in Figure 4 Schematic diagram of the effect after spraying the photoresist solution a second time along the X-axis at the pattern edge;

[0062] Figure 6 provided by an embodiment of the present invention in Figure 5 Schematic diagram of the effect after spraying the photoresist solution a third time along the X-axis in the middle of the pattern;

[0063] Figure 7 Schematic diagram of the spraying position of the coating nozzle provided by an embodiment of the present invention;

[0064] Figure 8 Schematic diagram of a system architecture for improving the photoresist coating uniformity provided by an embodiment of the present invention. Detailed implementation manners

[0065] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0066] Please refer to Figure 1 , this embodiment provides a method for improving the photoresist coating uniformity, including the following steps:

[0067] Step S1: Determine a wafer and perform pre-treatment to obtain a coating substrate;

[0068] Step S2: Configure the photoresist solution;

[0069] Step S3: Rotate the coating substrate and horizontally move the coating nozzle along the diameter direction of the coating substrate to spray the photoresist solution on the coating substrate;

[0070] Step S4: Dry the coating substrate after spraying the photoresist solution; wherein:

[0071] The injection volume of the coating nozzle is 10-50 ul / s, and the solid content of the photoresist solution is 15%.

[0072] In this embodiment, experiments have shown that, under the same other conditions, when the ejection volume of the glue - applying nozzle is controlled to be 10 - 50 ul / s and the solid content of the photoresist solution is configured to be 15%, the ejection volume is appropriate, and thus the speed at which the photoresist droplets collide with the glue - applying substrate is also appropriate. At this time, when the photoresist droplets are in the equilibrium stage (i.e., the stable state of the droplets) after colliding with the glue - applying substrate, they do not have enough kinetic energy to be converted into potential energy, that is, they cannot overcome the adsorption force of the glue - applying substrate, avoiding the situation where the entire droplet bounces up or part of the droplet splashes, thereby improving the uniformity of photoresist coating and avoiding waste of photoresist.

[0073] It should be noted that when the solid content of the photoresist solution is 15%, a relatively thick photoresist film layer can be obtained. During the spraying process, there is no need to increase the ejection volume of the glue - applying nozzle, thereby avoiding the situation where the entire droplet bounces up or part of the droplet splashes, avoiding waste of photoresist and improving the uniformity of photoresist coating.

[0074] To further illustrate the technical effects of the present invention, this embodiment is verified by the method of controlling variables. Specifically, the photoresist solutions used in the experiments of this embodiment are the same, the ejection angles of the nozzles are the same, the spraying steps are the same, and the distance from the glue - applying nozzle to the glue - applying substrate is also the same. To ensure the uniformity of photoresist coating, the angular velocity of the glue - applying substrate and the moving speed of the glue - applying nozzle have the same residence time at the corresponding steps in each experiment, that is, the only variable is the ejection volume of the glue - applying nozzle, and its variation range is 10 - 110 ul / s. Two experiments are carried out under the same conditions. The comparison between the experimental data and the ideal data can be seen in Figure 2 as shown. From Figure 2 it can be seen that the data obtained from the experiment when the ejection volume is in the range of 10 - 50 ul / s is very close to the ideal value. When the ejection volume is 60 - 110 ul / s, both experiments deviate from the ideal value. The experiment shows that as the ejection volume increases, the ejection speed of the glue - applying nozzle will also increase, and thus the collision speed of the photoresist droplets with the glue - applying substrate will increase. As a result, the photoresist droplets have enough kinetic energy to be converted into potential energy in the equilibrium stage after colliding with the glue - applying substrate, and finally overcome the adsorption force of the glue - applying substrate, causing the entire photoresist droplet to bounce up or part of the droplet to splash. Therefore, its experimental data will deviate significantly from the ideal value. Therefore, this embodiment can fully illustrate that when the ejection volume is 10 - 50 ul / s, when the photoresist droplets are in the equilibrium stage (i.e., the stable state of the droplets) after colliding with the glue - applying substrate, they do not have enough kinetic energy to be converted into potential energy, that is, they cannot overcome the adsorption force of the glue - applying substrate, avoiding the situation where the entire droplet bounces up or part of the droplet splashes, thereby improving the uniformity of photoresist coating and avoiding waste of photoresist.

[0075] To further illustrate the technical effects of the present invention, this embodiment is verified by the method of controlling variables. Specifically, in the experiments of this embodiment, the spraying angles of the nozzles used are the same, the spraying steps are the same, and the distances from the glue - applying nozzle to the glue - applying substrate are the same. To ensure the uniformity of photoresist coating, the angular velocity of the glue - applying substrate and the moving speed of the glue - applying nozzle have the same residence time at the corresponding steps in each experiment, that is, the only variable is the solid content of the photoresist, which are 4 groups of photoresist solutions with solid contents of 5%, 7%, 10% and 15% respectively. Four experiments are carried out under the same conditions. For the comparison between the experimental data and the ideal data, refer to Figure 3 as shown. From Figure 3 it can be seen that the thickness of the photoresist increases with the increase of the solid content and the spraying amount. When spraying with photoresist solutions with solid contents of 5% and 7%, the result is that as the spraying amount gradually increases, the change in the thickness of the photoresist is not significant. This is because when the solid content is low, the fluidity of the photoresist is relatively large, so it is difficult to form a thicker film layer. While 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 glue - applying nozzle, thereby avoiding the situation of the entire droplet bouncing or partial droplet splashing, avoiding photoresist waste and improving the uniformity of photoresist coating.

[0076] Furthermore, the step of determining a wafer and performing pre - treatment to obtain a glue - applying 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 glue - applying substrate; wherein: in the sulfuric acid - hydrogen peroxide mixture, the volume ratio of sulfuric acid to hydrogen peroxide is 1:1 to 50:1, and when the sulfuric acid - hydrogen peroxide mixture is used for wafer treatment, the temperature is 100°C to 180°C; in the sulfuric acid - ozone mixture, the ozone content is 1 to 50 ppm, and when the sulfuric acid - ozone mixture is used for wafer treatment, the temperature is 100°C to 180°C; in the hydrochloric acid - hydrogen peroxide mixture, the volume ratio of hydrochloric acid, hydrogen peroxide and deionized water is 1:1:1 to 1:10:100, and when the sulfuric acid - ozone mixture is used for wafer treatment, the temperature is 20°C to 80°C.

[0077] In this embodiment, before spraying the photoresist on the wafer, treating it with a sulfuric acid - hydrogen peroxide mixture, a sulfuric acid - ozone mixture or a hydrochloric acid - hydrogen peroxide mixture can micro - oxidize the wafer surface, achieving the purpose of passivating the material surface, making the wafer surface more stable and reducing the influence of air - molecule pollutants. Experiments have shown that after pretreatment with acidic substances, the pH value of the wafer surface decreases, which is beneficial to the photo - acid stability of the photoresist when spraying the photoresist, and can provide better lithography control process capabilities in subsequent processes.

[0078] Further, the duration for treating the wafer with a sulfuric acid hydrogen peroxide mixture, a sulfuric acid ozone mixture, or a hydrochloric acid hydrogen peroxide mixture is 30 s to 30 min.

[0079] It should be noted that the wafer can also be pretreated with anhydrous ethanol to isolate the wafer from the surrounding environment and avoid the adsorption of fine particles in the surrounding environment by the wafer.

[0080] Further, the preparation of the photoresist solution is specifically as follows: Mix AZ series photoresist, methyl ethyl ketone, and propylene glycol monomethyl ether acetate in a ratio of 1:1.5:0.5 to obtain a photoresist solution with a solid content of 15%.

[0081] Although the existing photoresist solution obtained by diluting AZ series photoresist with propylene glycol monomethyl ether acetate is suitable for the spraying process, the formed photoresist solution has too high fluidity, which is likely to affect the uniformity of spin coating; while the photoresist solution obtained by diluting AZ series photoresist with methyl ethyl ketone has too high viscosity, which is likely to generate a photoresist film layer with high roughness. In the above solution, the photoresist solution formed by mixing AZ series photoresist, methyl ethyl ketone, and propylene glycol monomethyl ether acetate in a ratio of 1:1.5:0.5 has a high evaporation rate and can greatly reduce the movement of photoresist droplets, so that a more uniform photoresist film can be formed during the spraying process.

[0082] Further, the rotation of the spin coating substrate and the horizontal movement of the spin coating nozzle along the diameter direction of the spin coating substrate to spray the photoresist solution on the spin coating substrate are specifically as follows: Determine the diameter of the spin coating substrate; Based on the diameter, determine the semi-normal distribution distance at which the spin coating nozzle sprays the photoresist solution to satisfy D = 2NT, where N is a positive integer, D is the diameter of the spin coating substrate, and T is the semi-normal distribution distance; Take the semi-normal distribution distance T as the step distance of the spin coating nozzle, and make the spin coating substrate rotate in cooperation, so that when the spin coating nozzle moves horizontally along the diameter direction of the spin coating substrate, the unit time for all areas on the spin coating substrate to be sprayed with the photoresist solution is the same; The unit time is to divide the area of the spin coating substrate at the step distance into several units, and the time for each unit to receive the spraying of the photoresist solution.

[0083] In this embodiment, by controlling the step distance of the spin coating nozzle to be the semi-normal distribution distance, the uniformity of the formed photoresist film layer can be ensured; Only by cooperating with the rotation of the spin coating substrate, the spin coating nozzle can realize the spin coating of the entire spin coating substrate.

[0084] In this embodiment, since the area to be sprayed is larger for the glue - coating substrate the farther it is from the center of the circle, to ensure that each unit on the glue - coating substrate receives the photoresist solution for the same duration of spraying, the residence time can be set according to the position of the glue - spraying nozzle relative to the glue - coating substrate. That is, when the glue - spraying nozzle is at the edge of the glue - coating substrate, its residence time is the longest, and when the glue - spraying nozzle is at the center of the glue - coating substrate, its residence time is the shortest.

[0085] In this embodiment, making D = 2NT can ensure that the center of the glue - coating substrate is directly below the glue - spraying nozzle, guaranteeing the uniformity of the overall glue - coating of the glue - coating substrate. Most of the photoresist solution sprayed by the glue - spraying nozzle can be received by the glue - coating substrate, improving the uniformity of photoresist coating while reducing the waste of photoresist solution.

[0086] Furthermore, the glue - coating operation can be completed when the glue - spraying nozzle reaches the center of the glue - coating substrate and finishes spraying the photoresist solution; it can also be set that the glue - spraying nozzle starts spraying from one - end edge of the glue - coating substrate, passes through the center along the diameter, and finishes spraying the photoresist solution when reaching the other - end edge of the glue - coating substrate. The residence times of the glue - spraying nozzle in the two glue - coating methods are different, and only the unit duration for all areas on the glue - coating substrate to be sprayed with the photoresist solution needs to be the same.

[0087] Furthermore, the semi - normal distribution distance for the glue - spraying nozzle to spray the photoresist solution is determined based on the diameter to satisfy D = 2NT. Specifically:

[0088] Based on the diameter, the semi - normal distribution distance for the glue - spraying nozzle to spray the photoresist solution is adjusted by adjusting the distance between the glue - spraying nozzle and the glue - coating substrate and the exit angle of the glue - spraying nozzle to satisfy D = 2NT.

[0089] Furthermore, the adjustment of the semi - normal distribution distance for the glue - spraying nozzle to spray the photoresist solution is specifically as follows: establish an X - Y axis coordinate system on a blank coating; use the glue - spraying nozzle to move along the X - axis on the blank coating and conduct a primary spraying of the photoresist solution to obtain a normal distribution pattern, and take the distance between the center and the edge of the normal distribution pattern as the semi - normal distribution distance; by adjusting the distance between the glue - spraying nozzle and the glue - coating substrate and the exit angle of the glue - spraying nozzle, the adjustment of the semi - normal distribution distance for the glue - spraying nozzle to spray the photoresist solution is realized.

[0090] Experiments have shown that to form a uniform and complete photoresist coating, multiple sprays need to be carried out with a semi - normal distribution distance as the span. For details, please refer to Figures 4 to 6 as shown. First, establish an X - Y axis coordinate system on a blank coating, and then let the glue - spraying nozzle move along the X - axis and conduct a primary spraying of the photoresist solution. At this time, the pattern obtained is as shown in Figure 4The pattern shown. Obviously, the obtained pattern presents a normal distribution. Here, along the downward direction of the Y-axis, the second spraying of the photoresist solution is performed along the X-axis at the edge of the pattern formed for the first time. At this time, the pattern as shown in Figure 5 can be obtained. Obviously, Figure 5 In the middle part of the entire pattern presented, there is almost no coverage of the photoresist, indicating that a spraying method with a normal distribution length as a cycle during the entire spraying process cannot obtain a uniform photoresist film layer.

[0091] Therefore, on the basis of the Figure 5 pattern, a third spraying is performed in the middle part thereof, and the finally obtained pattern is as shown in Figure 6 shown. Figure 6 It can be clearly seen that after three sprayings, the best glue coating effect is obtained in the middle part of the entire spraying area. Therefore, by controlling the step 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; only by cooperating with the rotation of the glue coating substrate, the glue coating nozzle can realize the glue coating of the entire glue coating substrate.

[0092] To further illustrate the technical features of the present invention, this embodiment is described through Figure 7 description. It can be seen from Figure 7 that the step distance of the glue coating nozzle is a semi-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 glue coating substrate is directly below the step path of the glue coating nozzle, ensuring the uniformity of the overall glue coating of the glue coating substrate, so that most of the photoresist solution sprayed by the glue coating nozzle can be received by the glue coating substrate, improving the uniformity of the photoresist coating while reducing the waste of the photoresist solution.

[0093] Furthermore, the angular velocity of the rotation of the glue coating substrate satisfies:

[0094]

[0095] In the formula, represents the adhesion force, which is related to the dynamic viscosity of the photoresist itself; represents the average mass of the photoresist droplets, which is related to the spraying amount of the glue coating nozzle; represents the distance from the center of the photoresist droplet to the center of the glue coating substrate, that is, the horizontal distance from the center of the photoresist droplet to the rotation axis. When the angular velocity of the rotation of the glue coating substrate satisfies the above, the photoresist particles will stably adhere to the glue coating substrate, avoiding uneven glue coating of the photoresist due to the centrifugal movement of the photoresist particles on the glue coating substrate.

[0096] Please refer to Figure 8 , this embodiment also proposes a system for improving the uniformity of photoresist coating, including:

[0097] A pretreatment module, which is used to pretreat the determined wafer to obtain a glue-coated substrate;

[0098] A solution preparation module, which is used to prepare a photoresist solution with a solid content of 15%;

[0099] A glue application nozzle, which is used to spray the photoresist solution on the glue-coated substrate;

[0100] A substrate turntable, which is used to carry the glue-coated substrate and can rotate;

[0101] A control module, which is used to make the glue-coated substrate rotate and make the glue application nozzle move horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate; meanwhile, control the spraying amount of the glue application nozzle to be 10 - 50 ul / s;

[0102] A drying module, which is used to dry the glue-coated substrate after spraying the photoresist solution.

[0103] Furthermore, the control module is used to make the glue-coated substrate rotate and make the glue application nozzle move horizontally along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate. Specifically:

[0104] Based on the input diameter of the glue-coated substrate and the semi-normal distribution distance at which the glue application nozzle sprays the photoresist solution, make the glue application nozzle move with the semi-normal distribution distance as the step distance, and make the glue-coated substrate rotate accordingly, so that when the glue application nozzle moves horizontally along the diameter direction of the glue-coated substrate, the unit time for all areas on the glue-coated substrate to be sprayed with the photoresist solution is the same;

[0105] The unit time is to divide the area of the glue-coated substrate at the step distance into several units, and the time for each unit to receive the spraying of the photoresist solution;

[0106] The diameter and the semi-normal distribution distance satisfy D = 2NT, where N is a positive integer, D is the diameter of the glue-coated substrate, and T is the semi-normal distribution distance.

[0107] The system architecture provided in this embodiment is simple. When the spraying amount of the glue application nozzle is controlled to be 10 - 50 ul / s and the solid content of the photoresist solution is configured to be 15%, the spraying amount is appropriate, so that the speed at which the photoresist droplets collide with the glue-coated substrate is also appropriate. At this time, when the photoresist droplets collide with the glue-coated substrate and 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 glue-coated substrate, avoiding the situation where the entire droplet bounces or part of the droplet splashes, thereby improving the uniformity of photoresist coating and avoiding waste of photoresist.

[0108] The above system also makes D = 2NT, thereby ensuring that the center of the substrate to be coated can be directly below the coating nozzle, ensuring the uniformity of the overall coating of the substrate to be coated, enabling most of the photoresist solution sprayed by the coating nozzle to be received by the substrate to be coated, improving the uniformity of photoresist coating while reducing the waste of the photoresist solution.

[0109] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A method for improving the coating uniformity of photoresist, characterized in that, It includes the following steps: Determine a wafer and perform pretreatment to obtain a glue-coated substrate; Prepare a photoresist solution; Rotate the glue-coated substrate and horizontally move the glue-spraying nozzle along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate; Dry the glue-coated substrate after spraying the photoresist solution; wherein: The spraying amount of the glue-spraying nozzle is 10 - 50 ul / s, and the solid content of the photoresist solution is 15%; The step of rotating the glue-coated substrate and horizontally moving the glue-spraying nozzle along the diameter direction of the glue-coated substrate to spray the photoresist solution on the glue-coated substrate is specifically: Determine the diameter of the glue-coated substrate; Based on the diameter, determine the semi-normal distribution distance for the glue-spraying nozzle to spray the photoresist solution to satisfy D = 2NT, where N is a positive integer, D is the diameter of the glue-coated substrate, and T is the semi-normal distribution distance; Using the semi-normal distribution distance T as the step distance of the glue-spraying nozzle, rotate the glue-coated substrate accordingly, so that when the glue-spraying nozzle horizontally moves along the diameter direction of the glue-coated substrate, the unit time for all areas on the glue-coated substrate to be sprayed with the photoresist solution is the same; The unit time is to divide the area of the glue-coated substrate at the step distance into several units, and the time for each unit to receive the spraying of the photoresist solution; The preparation of the photoresist solution is specifically: Mix AZ series photoresist, methyl ethyl ketone, and propylene glycol monomethyl ether acetate in a volume ratio of 1:1.5:0.5 to obtain a photoresist solution with a solid content of 15%; The angular velocity of the glue-applied substrate in cooperation with rotation Satisfies: In the formula, represents the adhesion force, which is related to the dynamic viscosity of the photoresist itself; represents the average mass of the photoresist droplet, which is related to the ejection amount of the coating nozzle; represents the distance from the center of the photoresist droplet to the center of the coating substrate, that is, the horizontal distance from the center of the photoresist droplet to the rotating shaft; The step of determining a wafer and performing pretreatment to obtain a glue-coated substrate is specifically: Determine a wafer; Treat the wafer 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-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 wafer treatment, 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 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 hydrochloric acid-hydrogen peroxide mixture is used for wafer treatment, the temperature is 20°C - 80°C.

2. The method for improving the coating uniformity of photoresist according to claim 1, wherein The time for treating the wafer with the sulfuric acid-hydrogen peroxide mixture, the sulfuric acid-ozone mixture, or the hydrochloric acid-hydrogen peroxide mixture is 30 s - 30 min.

3. A method for improving the coating uniformity of photoresist according to claim 1, characterized in that, Adjust the semi-normal distribution distance for the glue-spraying nozzle to spray the photoresist solution, specifically: Establish an X-Y axis coordinate system on a blank coating; Use the glue-spraying nozzle to move along the X axis on the blank coating and perform a first spraying of the photoresist solution to obtain a normal distribution pattern, and take the distance between the center and the edge of the normal distribution pattern as the semi-normal distribution distance; By adjusting the distance between the glue - applying nozzle and the glue - applying substrate and the exit angle of the glue - applying nozzle, the semi - normal distribution distance at which the glue - applying nozzle sprays the photoresist solution is adjusted.

4. A system for improving the coating uniformity of photoresist, characterized in that, It includes: A pre - treatment module for pre - treating the determined wafer to obtain a glue - applying substrate; A solution - preparation module for preparing a photoresist solution with a solid content of 15%; A glue - applying nozzle for spraying the photoresist solution on the glue - applying substrate; A substrate turntable for carrying the glue - applying substrate and being rotatable; A control module for rotating the glue - applying substrate and horizontally moving the glue - applying nozzle along the diameter direction of the glue - applying substrate to spray the photoresist solution on the glue - applying substrate; meanwhile, controlling the spraying amount of the glue - applying nozzle to be 10 - 50 ul / s; A drying module for drying the glue - applying substrate after spraying the photoresist solution; The control module for rotating the glue - applying substrate and horizontally moving the glue - applying nozzle along the diameter direction of the glue - applying substrate to spray the photoresist solution on the glue - applying substrate, specifically: Based on the input diameter of the glue - applying substrate and the semi - normal distribution distance at which the glue - applying nozzle sprays the photoresist solution, making the glue - applying nozzle move with the semi - normal distribution distance as the step distance, and making the glue - applying substrate rotate accordingly, so that when the glue - applying nozzle horizontally moves along the diameter direction of the glue - applying substrate, the unit time for all areas on the glue - applying substrate to be sprayed with the photoresist solution is the same; The unit time is to divide the glue - applying substrate into several units, and the time for each unit to receive the spraying of the photoresist solution; The diameter and the semi - normal distribution distance satisfy D = 2NT, where N is a positive integer, D is the diameter of the glue - applying substrate, and T is the semi - normal distribution distance; Preparing the photoresist solution specifically: Mixing AZ - series photoresist, methyl ethyl ketone, and propylene glycol monomethyl ether acetate in a volume ratio of 1:1.5:0.5 to obtain a photoresist solution with a solid content of 15%; The angular velocity of the glue - applied substrate in cooperation with rotation Satisfies: In the formula, represents the adhesion force, which is related to the dynamic viscosity of the photoresist itself; represents the average mass of the photoresist droplet, which is related to the ejection amount of the coating nozzle; represents the distance from the center of the photoresist droplet to the center of the coating substrate, that is, the horizontal distance from the center of the photoresist droplet to the rotating shaft; Determining a wafer and performing pre - treatment to obtain a glue - applying substrate, specifically: 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 glue - applying substrate; where: 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 wafer treatment, the temperature is 100℃ - 180℃; In the sulfuric acid - ozone mixture, the ozone content is 1 - 50 ppm, and when the sulfuric acid - ozone mixture is used for wafer treatment, the temperature is 100℃ - 180℃; 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 hydrochloric acid - hydrogen peroxide mixture is used for wafer treatment, the temperature is 20℃ - 80℃.

Images