40¿m Die Strength Characterization

Abstract

This paper characterizes the die strength of 40 mum silicon die with the intention to understand the behavior of the thin die to prevent die crack during package assembly. Die strength is measured by three-point bending test conducted using the universal tensile tester and the three-point bending jig. At first, a comparison of the influence between mechanical and laser dicing method to the die strength of 40 mum, 70 mum and 100 mum silicon die are investigated. Next, the effect of dry plasma etching on the die sidewall towards the die strength of 4 mum silicon die is also being explored. Apart from the die strength, the deflection of the die before breaking is measured to study the flexibility of 40 mum silicon die. In addition, surface morphology and silicon fractography are analyzed to examine the surfaces of silicon die. Finally, the samples are subjected to Raman spectroscopy to analyze the residual stress on the die sidewall. This investigation reveals that the die strength is dependent on the dicing method and surface treatment after dicing. Even though laser dicing weaken the die strength by 70% compares to mechanical dicing, the die strength of laser dicing can be improved up to 370% by the plasma sidewall etching treatment. It is also observed that there is a correlation between the fracture modes and the die strength.