ADVANCED PLASMA PROCESSING TECHNIQUES FOR IMPROVING DESCUM AND OTHER WLP PROCESS PERFORMANCE

摘要

Wafer level packaging (WLP) technology has been advancing by leaps and bounds over the past few years. As with all emerging technologies, the manufacturing challenges for building WLP devices can be great; moreover, the packaging and assembly processes are not always convergent, meaning that a solution that works for one type of WLP process may not be suitable for other processes. The challenge is to find solutions that are flexible enough to improve a wide range of WLP processes in order to be cost-effective. The WLP industry has found that a variety of commercially-available plasma treatments exist to address many of these challenges. Plasma processing can remove photo resist (PR) residue after development (a process commonly referred to as "descum" in the semiconductor industry), remove organic, metal or oxide contamination, generally clean the surface of the wafer before the next step in the process, roughen and activate the chemical bonds at the surface of the wafer in order to improve bondability, increase the wettability of the surface of the wafer, and increase the uniformity of liquid flow (such as liquid photo resist material) over the surface of the wafer. Moreover, data show that plasma technology is a convergent technology, where both established and emerging WLP processes can be improved in existing plasma systems (by changing, for example, plasma chemistries, flow rates, process pressures, power settings, and chamber configuration, etc.), and without the high costs usually associated with traditional front-end equipment capital equipment. Plasma processes can directly, and in some cases, dramatically improve the performance and reliability of the finished WLP package. This discussion will cover how plasma treatments can improve the performance of several common WLP processes, such as descum. In this way, plasma treatment is rapidly changing from an enhancing technology to an enabling one.