Side protection methods for wafers

Abstract

This invention discloses a method for protecting the side surface of a wafer. The wafer is placed on a rotatable platform, and the method includes at least the following steps: a spraying step, in which the nozzle of a spraying module is moved to the side of the wafer, with a non-perpendicular angle between the nozzle and the wafer, and a protective material is sprayed onto the side surface of the wafer through the nozzle; and a curing step, in which the protective material sprayed onto the side surface of the wafer is heated by a curing module to cure the protective material into shape; wherein, during the spraying and curing steps, the platform rotates synchronously, so that the spraying module and the curing module respectively perform full-circumference spraying and full-circumference curing on the side surface of the wafer, and the spraying and curing steps are repeated until the protective layer formed by the protective material reaches a target thickness, thereby preventing subsequent processes from etching the lines of the bare die due to the solution.

Description

Technical Field

[0001] This invention relates to the technical field of wafer protection methods, and more particularly to a method for protecting the sides of a wafer by spraying and curing materials. Prior Technology

[0002] Note that CoWoS (Chip on Wafer on Substrate) packaging is a 2.5D / 3D advanced chip packaging technology developed by TSMC. It mainly consists of two stages: chip-on-wafer (CoW) and interposer packaging (Wafer-on-Substrate (WoS). CoW involves stacking multiple chips on a silicon interposer, while WoS packages the stacked chips onto a substrate. This packaging technology can reduce chip size, lower power consumption, and improve computing performance, making it particularly suitable for high-performance applications such as AI chips.

[0003] However, in the past, when performing the CoW process, in order to prevent the circuitry of the die from being etched by the solution in subsequent processes, the side of the wafer was protected by encapsulation molding. However, this method is only suitable for small and medium-sized wafers and has drawbacks such as high cost, long mold processing time, and large equipment size, resulting in very high operating costs.

[0004] Therefore, in summary, the inventors of this invention have painstakingly researched, pondered, and designed a method for protecting the side of a wafer after many years of dedicated research, in order to improve upon the shortcomings of conventional technologies and thereby enhance their implementation and utilization in industry. Summary of the Invention

[0005] The main objective of this invention is to provide a method for protecting the side surface of a wafer. This method involves spraying a protective material onto the side surface of the wafer and then curing the material to form a protective layer on the wafer side surface. This prevents subsequent processes from etching the circuitry on the bare die due to the solution. Furthermore, this method is not limited by wafer size and is fast and requires smaller equipment, which can significantly reduce operating costs and increase production capacity.

[0006] Therefore, to achieve the above objectives, the present invention provides a method for protecting the side surface of a wafer, wherein the wafer is placed on a rotatable platform, and the method includes at least the following steps: a spraying step, wherein the nozzle of a spraying module is moved to the side of the wafer, and the nozzle has a non-perpendicular angle with the wafer, and a protective material is sprayed onto the side surface of the wafer through the nozzle; and a curing step, wherein the protective material sprayed onto the side surface of the wafer is heated through a curing module to cure the protective material into shape; wherein, when the spraying step and the curing step are performed, the platform is rotated synchronously so that the spraying module and the curing module respectively perform full-circumference spraying and full-circumference curing on the side surface of the wafer, and the spraying step and the curing step are repeated until the protective layer formed by the protective material reaches a target thickness.

[0007] As described above, the method for protecting the side of a wafer includes a placement and positioning step before the spraying step, in which the wafer is placed on the platform and the platform is fixed to the wafer by vacuum adsorption.

[0008] The protection method for the wafer side described above, wherein the included angle is approximately 15 to 75 degrees.

[0009] As described above regarding the protection method for the wafer side, the curing module is a UV lamp.

[0010] As described above regarding the protection method for the wafer side, the rotation speed of the platform is determined by the viscosity and coating amount of the protective material, and the rotation speed is approximately 0.5~10 rpm.

[0011] The method for protecting the side of a wafer described above, wherein the thickness of the target is approximately 5 to 10 µm.

[0012] As described above regarding the protection method for the wafer side, the spraying step involves applying the protective material in multiple small applications, rather than applying all of the protective material at once.

[0013] As described above regarding the protection method for the wafer side, the platform is further equipped with a heating unit. During the spraying process, the heating unit simultaneously heats the material to pre-cure it.

[0014] As described above regarding the protection method for the side of a wafer, the heating unit is a heating plate.

[0015] The method for protecting the side of a wafer described above uses a medium-to-high viscosity ink as the protective material.

[0016] In summary, the present invention will be described in detail below with reference to specific embodiments. The following embodiments are merely illustrative and are not intended to limit the scope of protection of the present invention. Those skilled in the art will readily understand that various non-critical parameters can be changed or adjusted to produce substantially the same results. Simple Explanation of the Diagram

[0017] Figure 1 is a schematic flowchart of the wafer side protection method of the present invention. Figures 2A to 2F are schematic diagrams illustrating the implementation of the wafer side protection method of the present invention. Figure 3 is a first partial schematic diagram of the wafer side protection method of the present invention. Figure 4 is a second partial schematic diagram of the wafer side protection method of the present invention. Implementation

[0018] The embodiments of the present invention will be described below with reference to the figures shown. This description is not intended to limit the embodiments of the present invention, but rather to illustrate one example of the present invention.

[0019] First, please refer to Figures 1 to 2F. This invention provides a method for protecting the side surface of a wafer 10, which is placed on a rotatable platform 20 (as shown in Figure 2A). The method includes at least the following steps: a spraying step S1, in which a spray nozzle 30 of a spraying module is moved to the side of the wafer 10 (as shown in Figure 2B), and the spray nozzle 30 forms a non-perpendicular angle R with the wafer 10 (as shown in Figure 2C), and a protective material 40 is sprayed onto the side surface 11 of the wafer 10 through the spray nozzle 30; and a curing step S2, in which the protective material 40 sprayed onto the side surface 11 of the wafer 10 is heated through a curing module 50 (as shown in Figure 2E). The protective material 40 is cured and formed. During the spraying step S1 and the curing step S2, the platform 20 rotates synchronously so that the spraying module and the curing module 50 respectively spray the entire periphery of the side surface 11 of the wafer 10 (as shown in Figure 2D) and cure the entire periphery (as shown in Figure 2F). The spraying step S1 and the curing step S2 are repeated until the protective layer 60 formed by the protective material 40 reaches a target thickness. Therefore, the wafer side protection method of the present invention can use dry process direct writing technology to form the protective layer 60 on the side surface 11 of the wafer 10, and replaces the conventional packaging molding method to prevent the subsequent process from etching the lines of the bare die due to the solution.

[0020] In detail, before the spraying step S1, a placement and positioning step S0 is performed, in which the wafer 10 is placed on the platform 20, and the platform 20 is fixed to the wafer 10 by vacuum adsorption. This placement can be done by a person or a robotic arm. Next, the nozzle 30 is moved to the side of the wafer 10, and the nozzle 30 is tilted to face the side 11 of the wafer 10, creating an angle R (approximately 15-75 degrees) to achieve a better spraying contact angle. This facilitates the adhesion of the protective material 40 (e.g., ink) to the side 11 and prevents it from dripping due to gravity. The protective material 40 is then sprayed onto the side 11 through the nozzle 30. Simultaneously, the platform 20 rotates to ensure that the nozzle 30 sprays the entire circumference of the side 11, ensuring that the entire side 11 is covered with the protective material 40. After spraying... After completion, the protective material 40 sprayed on the side 11 is heated and cured by the curing module 50 (e.g., a UV lamp). At the same time, the platform 20 rotates to allow the curing module 50 to cure the protective material 40 sprayed on the side 11 around its entire circumference, so that the protective material 40 is cured and formed. By repeatedly performing the spraying step S1 and the curing step S2, that is, after the protective material 40 is sprayed around the side 11, the curing step S2 is performed on the protective material 40, and after the protective material 40 is cured around the side 11, the spraying step S1 is performed again. This process is repeated until the protective layer 60 formed by the protective material 40 reaches a target thickness, preferably about 5 to 10 µm. The rotation speed of the platform 20 is determined according to the viscosity of the protective material 40 and the amount of spraying, and the rotation speed is about 0.5 to 10 rpm.

[0021] However, in addition to the aforementioned method of achieving a better spray contact angle to facilitate the adhesion of the protective material 40 to the side 11, the wafer side protection method of the present invention can also avoid the occurrence of sagging by the following means:

[0022] 1. Selection of the protective material 40: The protective material 40 is made of medium-high viscosity ink, with a viscosity of approximately 5000~12000 cP, to resist gravity;

[0023] 2. Multiple spraying: The protective material 40 is sprayed in multiple small amounts, rather than all of it in one go. For example, as shown in Figure 3, about 1 / 3 of the target thickness can be sprayed at once, and three sprayings (such as the protective material 41, 42, and 43) can be applied to achieve the target thickness.

[0024] 3. Pre-curing: Using the platform 20 with a heating unit (not shown), when the spraying step S1 is performed, the protective material 40 is simultaneously heated by the heating unit to pre-cur it. Since the pre-curing is a low-energy curing method, it only forms a film on the surface of the protective material 40 to limit the dripping. As shown in Figure 4, when the first layer of protective material 41 is sprayed on the side 11, it will be heated by the heating unit (e.g., heating plate) to form a film on the surface of the protective material 41, thus completing the pre-curing of the first layer of protective material 41. Then, similarly, the second layer of protective material 42 and the third layer of protective material 43 are sprayed in sequence. After the three layers of protective material 41, 42, and 43 are sprayed, the curing step S2 is performed, which uses a higher-energy UV lamp for curing, so that the protective materials 41, 42, and 43 form the protective layer 60.

[0025] In addition, the above methods can be combined to ensure that sagging is avoided.

[0026] Therefore, the present invention does provide a method for protecting the side of a wafer. By spraying a protective material onto the side of the wafer and then curing the protective material, a protective layer is formed on the side of the wafer after curing. This prevents the circuitry on the bare die from being etched by the solution in subsequent processes. At the same time, the method for protecting the side of a wafer is not limited by the wafer size, and the operation is fast and the equipment is small, which can greatly reduce the operating cost.

[0027] However, the above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the description of the invention shall still fall within the scope of the patent of the present invention.

[0028] 10: Wafer 11: Side view 20: Platform 30: Sprayer Head 40, 41, 42, 43: Protective materials 50: Curing Module 60: Protective layer R: included angle S0: Placement and Positioning Steps S1: Spraying Steps S2: Curing Step

Claims

1. A method for protecting the side surface of a wafer, the wafer being placed on a rotatable platform, and the method comprising at least the following steps: a spraying step, wherein a spray nozzle of a spraying module is moved to the side of the wafer, the spray nozzle having a non-perpendicular angle with the wafer, and a protective material is sprayed onto the side surface of the wafer through the spray nozzle; and a curing step, wherein the protective material sprayed onto the side surface of the wafer is heated through a curing module to cure the protective material into shape; wherein, During the spraying and curing steps, the platform rotates synchronously, allowing the spraying module and the curing module to spray and cure the entire side of the wafer, respectively. The spraying and curing steps are repeated until the protective layer formed by the protective material reaches a target thickness. The rotation speed of the platform is determined by the viscosity of the protective material and the amount of material sprayed.

2. The method for protecting the side of a wafer as described in claim 1, wherein a placement and positioning step is performed before the spraying step, wherein the wafer is placed on the platform and the platform is fixed to the wafer by vacuum adsorption.

3. The method for protecting the side of a wafer as described in claim 1, wherein the included angle is approximately 15 to 75 degrees.

4. The method for protecting the side of a wafer as described in claim 1, wherein the curing module is a UV lamp.

5. The method for protecting the side of a wafer as described in claim 1, wherein the rotation speed is approximately 0.5 to 10 rpm.

6. A method for protecting the side of a wafer as described in claim 1, wherein the target thickness is approximately 5 to 10 µm.

7. The method for protecting the side of a wafer as described in claim 1, wherein the coating step involves applying the protective material in multiple small applications, rather than applying all of the protective material at once.

8. A method for protecting the side of a wafer as described in any one of claims 1 to 7, wherein the platform is further equipped with a heating unit, which heats the protective material during the spraying step to pre-cure it.

9. The method for protecting the side of a wafer as described in claim 8, wherein the heating unit is a heating plate.

10. A method for protecting the side of a wafer as described in any one of claims 1 to 7, wherein the protective material is a medium-to-high viscosity ink.

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