Adhesion studies of low-k silsesquioxane

As the dimension of IC devices continues to shrink, interconnection delay becomes a limiting factor to increase device speed. Therefore, it is necessary to use low-dielectric-constant (low-k) materials to reduce the capacitance between the metal interconnection. In this work, two kinds of low-k silisesquioxane have been investigated: Methylsilsesquioxane (MSQ) and Hydrogen silisesquioxane (HSQ). The adhesion between silicon nitride (Si ₃N₄) and low-k MSQ or HSQ has been examined. The adhesion strength can be improved by various plasma treatments on top of the silisesquioxane. The adhesion strength between MSQ and Si₃N ₄ can be increased by NH3 or H2 plasma treatment. On the other hand, the adhesion strength between HSQ and Si₃N₄ is only increased by NH3 treatment effectively. Surface properties and electrical characterization of low-k silisesquioxane have also been examined after various plasma treatments.