Coating method of wafer, storage medium, and coating apparatus for semiconductor

Abstract

The application provides a wafer coating method, a storage medium and a semiconductor coating equipment, wherein the wafer coating method comprises the following steps: providing a wafer and mounting the wafer on a rotating table of the coating equipment; driving the wafer to rotate at a first speed and coating a surface wetting agent to one side of the wafer; when the coating of the surface wetting agent is completed, driving the wafer to reduce the speed to a second speed within a first preset time and rotating the wafer at the second speed for a second preset time, wherein the first preset time is less than the second preset time; and coating photoresist on the side of the wafer provided with the surface wetting agent. After the surface wetting agent is coated on one side of the wafer, the wafer is driven to reduce the speed to the second speed within the first preset time, so that the wafer surface wetted by the surface wetting agent is naturally restored to a uniform temperature distribution and a liquid film state in a low shear force environment, thereby creating a flat substrate for subsequent photoresist coating.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a wafer coating method, a storage medium, and a semiconductor coating apparatus. Background Technology

[0002] In the semiconductor manufacturing industry, photoresist lithography is a special type of lithography technology, specifically referring to lithography processes where the photoresist coating thickness is greater than 5μm. Due to its unique thickness advantage, this process has been widely used in three core areas: advanced packaging, microelectromechanical systems (MEMS), and power devices.

[0003] However, due to the high solvent content and high viscosity of photoresist, "color pattern" defects are easily generated during the coating process, which manifest as rainbow-colored stripes or irregular color blocks on the film surface, seriously affecting the quality of subsequent photolithography patterns. Summary of the Invention

[0004] The problem solved by this invention is the "color streaks" defect in existing wafer coating methods.

[0005] To address the above problems, this invention provides a wafer coating method, applied to semiconductor coating equipment, the coating method comprising: Provide a wafer and mount the wafer onto the rotary table of the coating equipment; The wafer is driven to rotate at a first speed, and a surface wetting agent is applied to one side of the wafer; After the surface wetting agent is applied, the wafer is driven to decelerate to a second speed within a first preset time, and rotates at the second speed for a second preset time, wherein the first preset time is less than the second preset time; Photoresist is coated on the side of the wafer where the surface wetting agent is disposed.

[0006] Optionally, the range of the first speed is 300rpm-800rpm.

[0007] Optionally, the second speed ranges from 10 rpm to 50 rpm.

[0008] Optionally, the first preset time ranges from 0.03s to 0.1s; the second preset time ranges from 0.5s to 2s.

[0009] Optionally, the photoresist film thickness is not less than 5 μm.

[0010] Optionally, before driving the wafer to rotate at the first speed, the coating method further includes: The rotating stage is controlled to rotate to drive the wafer to rotate at a third speed, the third speed being greater than the second speed and less than the first speed.

[0011] Optionally, after coating the side of the wafer with the surface wetting agent with photoresist, the coating method further includes: The wafer is driven to rotate at a fourth speed for a third preset time to allow the photoresist to initially level out, wherein the fourth speed ranges from 10 rpm to 100 rpm and the third preset time ranges from 10 seconds to 30 seconds.

[0012] Optionally, after driving the wafer to rotate at a fourth speed for a third preset time, the coating method further includes: The wafer is driven to rotate at a fifth speed to remove excess adhesive. The fifth speed ranges from 2000 rpm to 3000 rpm.

[0013] Optionally, after removing excess adhesive, the coating method further includes: edge trimming of the wafer and controlling the wafer to rotate at the fifth speed for final spin drying.

[0014] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0015] This application also provides a semiconductor coating apparatus, the coating apparatus including a rotating stage and a controller, the controller being connected to the rotating stage for performing the steps of the method described in any of the above claims.

[0016] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages: The wafer coating method provided in this application involves coating one side of the wafer with a surface wetting agent, then driving the wafer to decelerate to a second speed within a first preset time, and rotating it at the second speed for a second preset time. This allows the wafer surface, wetted by the surface wetting agent, to naturally recover a uniform temperature distribution and liquid film state under low shear force, creating a smooth substrate for subsequent photoresist coating. This step requires no additional heating or gas treatment; surface homogenization can be achieved simply by changing the rotational dynamics. The process is simple and has low energy consumption. Attached Figure Description

[0017] Figure 1 An optical microscope image of surface color defects in photoresist in existing technology; Figure 2 A schematic flowchart of a wafer coating method provided in an embodiment of this application; Figure 3 An optical microscope image of the photoresist surface after being fabricated using the coating method provided in the embodiments of this application. Detailed Implementation

[0018] To make the above-mentioned objectives, features and structures of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0019] Traditional processes dictate that photoresist should be applied immediately after spraying the surface wetting agent to avoid delays and reduced production capacity. However, the applicant's extensive experiments have revealed that the surface wetting agent spraying step itself subtly impacts the wafer surface condition: First, the evaporation of the surface wetting agent on the wafer surface carries away heat, creating a minute temperature gradient with a difference of several degrees between the center and edge. Second, the shear force generated by the high-speed rotation of the airflow causes microscopic inhomogeneities in the distribution of the surface wetting agent. These microscopic surface inhomogeneities are amplified by the photoresist during subsequent photoresist application, contributing to uneven solvent evaporation and stress concentration, ultimately manifesting as macroscopic color-marking defects after baking. Specifically, as shown below... Figure 1 As shown, Figure 1 This is an optical microscope image of the color pattern defects on the surface of photoresist in the prior art.

[0020] Therefore, this application provides a wafer coating method, a storage medium, and a semiconductor coating apparatus to solve the aforementioned technical problems, as detailed below: Please see Figure 2 , Figure 2 This is a schematic flowchart of a wafer coating method provided in an embodiment of this application. The embodiment of this application provides a wafer coating method applied to semiconductor coating equipment. The coating method includes the following steps: S110. Provide a wafer and mount the wafer onto the rotating stage of the coating equipment.

[0021] The wafer is placed on the rotating stage of the coating chamber of the coating equipment.

[0022] S120, drive the wafer to rotate at a first speed and apply a surface wetting agent to one side of the wafer.

[0023] The rotating stage is controlled to drive the wafer to rotate at 80 rpm, and surface wetting agent is sprayed onto the center of the wafer through the Reduce Resist Consumption (RRC) nozzle. Then the wafer is driven to rotate at the first speed so that the surface wetting agent can evenly cover the wafer surface, providing a good spreading base for subsequent adhesive coating.

[0024] The first speed range is 300 rpm to 800 rpm. In some embodiments, the first speed can be 400 rpm, 500 rpm, 600 rpm, etc. The specific setting can be set according to the actual situation, and no specific limitation is made here.

[0025] In some other embodiments, before driving the wafer to rotate at a first speed, the coating method further includes controlling the rotation of a rotating stage to drive the wafer to rotate at a third speed, the third speed being greater than the second speed and less than the first speed.

[0026] Understandably, the step of driving the wafer to rotate at the third speed is performed before the surface wetting agent is applied, that is, before driving the wafer to rotate at 80 rpm. By pre-rotating the wafer at the third speed before applying the surface wetting agent, the wafer can enter a stable rotational state before the coating process begins, thereby improving the uniformity and process stability of the subsequent surface wetting agent coating process and avoiding problems such as uneven film layer and abnormal edges caused by fluctuations in rotation speed or unstable wafer orientation.

[0027] The third speed ranges from 1500 rpm to 2500 rpm. In some embodiments, the third speed can be 2000 rpm, etc. The specific setting can be adjusted according to the actual situation, and no specific limitation is made here.

[0028] S130. After the surface wetting agent is applied, the wafer is driven to slow down to the second speed within a first preset time, and rotates at the second speed for a second preset time, wherein the first preset time is less than the second preset time.

[0029] After the surface wetting agent is applied, the wafer is driven to decelerate to a second speed within a first preset time, and then rotated at the second speed for a second preset time. In other words, after spraying the surface wetting agent, photoresist is not applied immediately; instead, the wafer is rotated at the second speed for a second preset time. This allows the surface of the wafer, wetted by the surface wetting agent, to naturally recover a uniform temperature distribution and liquid film state under low shear force, creating a smooth substrate for subsequent photoresist coating. This step requires no additional heating or gas treatment; surface homogenization is achieved simply by changing the rotational dynamics, resulting in a simple process with low energy consumption.

[0030] Infrared thermal imaging monitoring showed that the surface temperature difference was about 2.5°C at the end of the spraying of the surface wetting agent. After 15 seconds of standing at low speed, the temperature difference decreased to less than 0.4°C.

[0031] The temperature of the surface wetting agent and the wafer are both 22°C. The temperature difference is caused by the volatilization of the surface wetting agent. Reflow is beneficial to the uniform distribution of the surface wetting agent and also to the improvement of the temperature uniformity of the wafer.

[0032] Understandably, driving the wafer to slow down to a second speed within a first preset time significantly reduces the airflow shear force generated by high-speed rotation during RRC spraying, leaving the wafer surface in a near-static state. Under this low-shear-force environment, the following advantages can be achieved: Temperature equalization: Local temperature deviations caused by the volatilization of surface wetting agents can be naturally restored to uniformity through heat conduction, without interference from forced convection, thus reducing the radial temperature gradient on the wafer surface to within ±0.5℃.

[0033] Uniform liquid film rearrangement: The trace amounts of surface wetting agent remaining on the wafer surface spontaneously rearrange under the driving force of surface tension, achieving a more uniform film distribution.

[0034] Surface stress release: The minute surface disturbances caused by high-speed rotation are fully smoothed out, and the film surface condition tends to stabilize.

[0035] Simple and energy-saving process: This step achieves surface homogenization through physical speed reduction only, without the need to turn on heating lamps or introduce special gases. The process is simple and consumes less energy.

[0036] The second speed ranges from 10 rpm to 50 rpm, and in some embodiments, the second speed is preferably 30 rpm. It is understood that the specific setting of the second speed can be adjusted according to actual conditions, and no specific limitations are imposed here.

[0037] The first preset time range is 0.03s-0.1s; this can achieve a rapid response decrease in wafer rotation speed, realizing instantaneous deceleration, and also ensure that it completes a smooth and controllable deceleration process within this time period.

[0038] The second preset time ranges from 0.5s to 2s. In some embodiments, the second preset time is preferably 1s. It is understood that the specific setting of the second preset time can be set according to the actual situation, and no specific limitation is made here.

[0039] S140. Coat the side of the wafer where the surface wetting agent is located with photoresist.

[0040] After the wafer is driven to rotate at the second speed for the second preset time, the wafer surface has reached the ideal state. At this time, the added photoresist can be evenly spread, and the subsequent solvent evaporation is more consistent. The photoresist coating process should be performed immediately. The specific process is as follows: first, rotate the wafer at 1000 rpm for 0.2s. After the photoresist arm is in place, perform static photoresist coating for 1s. Then, rotate at 2100 rpm for 3.3s to complete the photoresist spin coating.

[0041] The thickness of the photoresist is greater than 5 μm.

[0042] In some embodiments, after coating the wafer with photoresist on the side where the surface wetting agent is disposed, the coating method further includes: driving the wafer to rotate at a fourth speed for a third preset time to allow the photoresist to initially level out, wherein the fourth speed ranges from 10 rpm to 100 rpm, and the third preset time ranges from 10 seconds to 30 seconds. A low-speed reflow step allows the photoresist to initially level out under the action of surface tension.

[0043] In some embodiments, after driving the wafer to rotate at a fourth speed for a third preset time, the coating method further includes: driving the wafer to rotate at a fifth speed to remove excess adhesive; wherein the fifth speed is in the range of 2000rpm-3000rpm.

[0044] In some embodiments, after removing excess adhesive, the coating method further includes: edge trimming of the wafer and controlling the wafer to rotate at a fifth speed for final spin drying; the coating process is completed by wafer edge trimming and final spin drying.

[0045] This application provides a detailed description using a specific embodiment. Specifically: First, the wafer is driven to rotate at 2000 rpm for 1 second to complete rotation preparation; then, the wafer speed is adjusted to 80 rpm and maintained for 10 seconds, during which RRC coating is performed. Afterward, it is rotated at 500 rpm for 1 second to complete spin-drying. After RRC coating, the wafer speed is instantly reduced from 500 rpm to 30 rpm and maintained for 1 second. Next, the wafer is driven to rotate at 1000 rpm for 0.2 seconds. After the photoresist arm is in position, static coating is performed for 1 second. After coating, it is rotated at 2100 rpm for 3.3 seconds for spin-drying. Then, the wafer speed is reduced to 100 rpm and rotated for 1 second to complete the reflow process after coating; next, it is rotated at 1314 rpm for 30 seconds to achieve high-speed spin-drying, followed by low-speed rotation at 800 rpm for 15 seconds to complete EBR edge removal; finally, it is rotated at 2000 rpm for 5 seconds to complete the final spin-drying. After the above process, visual inspection of the wafers after hot plate baking showed no color defects. The processed wafer surface showed... Figure 3 , Figure 3 An optical microscope image of the photoresist surface after being fabricated using the coating method provided in the embodiments of this application.

[0046] This application also provides a readable storage medium storing computer-executable instructions. When the computer-executable instructions are read and executed by a processor, the readable storage medium is controlled to implement the wafer coating method as described in the above embodiments.

[0047] If the functionality is implemented as a software module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned readable storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0048] This application also provides a semiconductor coating apparatus, which includes a rotating stage and a controller. The controller is connected to the rotating stage and is used to perform the steps of the method described in any of the above claims. The specific steps are described above and will not be repeated here.

[0049] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A wafer coating method, applied to a coating equipment, characterized in that, The coating method includes: Provide a wafer and mount the wafer onto the rotary table of the coating equipment; The wafer is driven to rotate at a first speed, and a surface wetting agent is applied to one side of the wafer; After the surface wetting agent is applied, the wafer is driven to decelerate to a second speed within a first preset time, and rotates at the second speed for a second preset time, wherein the first preset time is less than the second preset time; Photoresist is coated on the side of the wafer where the surface wetting agent is disposed.

2. The coating method according to claim 1, characterized in that, The first speed ranges from 300 rpm to 800 rpm.

3. The coating method according to claim 1, characterized in that, The second speed range is 10 rpm to 50 rpm.

4. The coating method according to claim 1, characterized in that, The first preset time ranges from 0.03s to 0.1s; the second preset time ranges from 0.5s to 2s.

5. The coating method according to any one of claims 1 to 4, characterized in that, The thickness of the photoresist film is not less than 5 μm.

6. The coating method according to any one of claims 1 to 4, characterized in that, Prior to driving the wafer to rotate at the first speed, the coating method further includes: The rotating stage is controlled to rotate to drive the wafer to rotate at a third speed, the third speed being greater than the second speed and less than the first speed.

7. The coating method according to any one of claims 1 to 4, characterized in that, After coating the side of the wafer with the surface wetting agent with photoresist, the coating method further includes: The wafer is driven to rotate at a fourth speed for a third preset time to allow the photoresist to initially level out, wherein the fourth speed ranges from 10 rpm to 100 rpm and the third preset time ranges from 10 seconds to 30 seconds.

8. The coating method according to claim 7, characterized in that, After driving the wafer to rotate at a fourth speed for a third preset time, the coating method further includes: The wafer is driven to rotate at a fifth speed to remove excess adhesive. The fifth speed ranges from 2000 rpm to 3000 rpm.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 8.

10. An adhesive coating device, characterized in that, The adhesive application equipment includes a rotating stage and a controller, the controller being connected to the rotating stage for performing the steps of the method as described in any one of claims 1 to 8.

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