Thermal Stress Control in Cu Dual Damascene Interconnects with Low-k Organic Polymer Film

Abstract

We investigated the stability of organic low-/Cu dual damascene (DD) interconnects under thermal cycle stresses and concluded that the thermal stability was improved by adding a stress control layer (SCL) to the organic polymer intralayer dielectric (ILD) film . At high temperature, Cu vias suffered from large tensile stress in the organic polymer ILD film that expanded and left voids in the Cu vias. A large tensile stress was applied to the organic film at to create voids in the organic film around the vias. The introduction of SCL with a coefficient of thermal expansion and modulus near those of the polymer and Cu reduced the tensile stresses in the Cu vias at high temperature, as well as in the polymer at very low temperature. A well-designed SCL resulted in robust high performance Cu DD interconnects with low- organic ILD films.