In the precise field of semiconductor manufacturing, the processes of wafer thinning and dicing are critical, directly influencing product performance and reliability. In these processes, UV films and blue films serve as indispensable auxiliary materials, playing vital roles. This article explores the characteristics of these two films and their applications in chip manufacturing, providing the industry with a comprehensive understanding.
Film Material Selection in Wafer Thinning and Dicing
Before wafer thinning, an adhesive film applied to the front of the wafer stabilizes the chip and protects its integrity during back grinding. After grinding, the wafer thickness can be reduced from approximately 700μm to 200μm, or even lower, to meet various application requirements. During the dicing stage, the film on the back ensures the safety of the dies, preventing cutting damage and displacement risks.
UV Film and Blue Film: A Comparative Analysis
UV Film: This special film exhibits unique properties by blocking ultraviolet light and short-wavelength visible light. UV films are categorized by adhesive strength into high, medium, and low types. High-adhesive UV films, when not exposed to UV light, have a peel strength of 5,000 to 12,000 mN/20mm, which significantly drops to below 1,000 mN/20mm after UV exposure. In contrast, low-adhesive UV films, after UV exposure, reduce peel strength to about 100 mN/20mm, with no residue, facilitating easy chip handling. The extensibility of UV films ensures that water does not penetrate between the dies and the film during dicing, enhancing process stability.
Blue Film: Initially named for its color, blue film has evolved to include various colors and applications. Its peel strength typically ranges between 1,000 and 3,000 mN/20mm, but it is prone to residual adhesive issues due to temperature variations. Although cost-effective, the adhesive’s sensitivity to temperature changes limits its use in some precise processes.
Application Scenario Analysis
For small-sized chip thinning and dicing, UV films are preferred due to their controllable adhesive strength, effectively preventing chip loss or damage during handling. For larger chips or wafers directly entering the post-packaging process, blue films provide stable support due to their higher initial adhesive strength. Particularly in RFID chip applications, where chip sizes are smaller than 750μm×750μm, UV films are more commonly used.
Challenges and Solutions in Practice
When using the D-184 low-adhesive UV film for flip-chip packaging, chip loss can occur due to insufficient UV lamp power. To overcome this challenge, the following measures are recommended:
1. Clean UV lamp tubes and covers to optimize light reflection.
2. Regularly replace UV lamp tubes to ensure equipment performance.
3. Increase the power per unit length of UV lamp tubes to meet the standard of 80~120W/cm.
4. Rotate the lamp tubes periodically to ensure balanced light distribution.
By precisely controlling the exposure time and intensity of UV films, not only are technical issues in production resolved, but wafer manufacturing efficiency and quality are also significantly improved.
Conclusion
In conclusion, UV and blue films play distinct roles at different stages of wafer manufacturing. Understanding and mastering the properties of these films are crucial for optimizing production processes and enhancing product performance. With continuous technological advancements, more innovative materials are expected to join this field, propelling the semiconductor industry towards higher precision and efficiency.
Post time: Aug-02-2024
