Development of all new structure of Dicing Die Attach Film (DDAF) for Stealth Dicing and Cool Expansion processes

Abstract

Mobile devices, including smart phones and tablets, are increasing in complexity and require ever greater amounts of memory storage. In the past the challenge of higher memory densities and increase functionality has been met through miniaturization of device features, but as we reach the physical limits of feature size, packaging is being relied on more and more to achieve the necessary higher densities in memory and additional device functionality. Thin dies reduce overall package height, however, to achieve high memory densities in low profile packages the die attach material must have an even, thin bond line thickness. DAF (Die Attach Film) is an excellent solution. LINTEC developed an all new DDAF (Dicing Die Attach Film) with thinner DAF for CE (Cool Expansion) process. Conventional tape has a large area of exposed DAF surface which creates the risk of wafer and / or equipment contamination if DAF flies off during the CE process. We developed an all-new tape structure which is compatible with the SD (Stealth Dicing) and CE processes. The structure consists of DAF, IB (Intermediate Basefilm), and dicing tape. The diameter of the DAF and IB is close to the wafer diameter size to significantly reduce the risk of DAF separation and ejection during CE. We considered IB to improve DAF separation and it was found that a thinner IB layer is a good approach to separate DAF effectively. We can adjust adhesion between the DAF and the IB by changing the material properties of the IB, as an effective means to control die-fly and pick-up.