Laser DAF Cut: A Breakthrough Approach of Die Attach Film Singulation for Thin Wafers

Abstract

Today, semiconductor world is becoming more inclined to thinner Integrated Circuit (IC) packages. IC packages will require thinning of the internal configuration of the package, which involves the die or the wafer and the adhesive material, which is the Die Attach Film (DAF). Aligned to this, as wafers goes thinner it becomes more of a challenge in process development especially during its preparatory stages, such as wafer back grinding and sawing processes. As the die becomes smaller and thinner wafer sawing process should have minimum effect on the mechanical integrity of the silicon so as not to alter its quality. New technologies were introduced so as to adopt to this development trend, one of this is the Dicing Before Grinding (DBG). Compared to the normal wafer preparation process that is wafer back grinding before wafer sawing, DBG flow is wafer sawing first prior wafer back grinding processes. The application of DBG technology eliminates the mechanical draw backs of the conventional wafer sawing process. In addition, with the use of DAF for thinner packages, DBG was developed together with the Die Attach Film (DAF) cutting solution, which is Laser DAF Cutting.  DAF are separated using Laser as a cutting medium to address potential processability problems that may occur on the conventional mechanical blade saw. The paper discuss the Laser DAF cut development that covers the Design of Experiments (DoE) to understand the different characteristics of Laser DAF solution and be validated through actual simulation and wafer processing. The paper will also cover the interaction of different DAF thicknesses and Laser DAF parameters in order to define the critical characteristics so as to understand the behavior of different laser DAF parameters in achieving optimal DAF cutting process responses.