Experimental Determination of the Toughness of Crack Stop Structures

In this paper we present an experimental approach to the determining the toughness of crackstop structures. It is shown that methods used for adhesion testing can be adapted to quantitatively determine the effective toughness of different crackstop designs. A design based on metal pad shapes connected together with vias is shown to be capable of producing toughnesses that are 3.75 times the intrinsic toughness of the dielectric. In an optimized design we obtain a further 60% improvement in the crackstop toughness. The experiments presented provide an accurate way of determining the effectiveness of crackstop designs in arresting dicing flaws driven by the stresses present in different packages.