Impact of CMP Polish and pCMP Cleaning on Adhesion of SiCN Capping Layer on PECVD-Derived Porous OSG and Copper

The development of robust integration processes for low-dielectric-constant materials is critical in order to meet the ITRS timeline. For 45 nm and beyond, the roadmap dictates use of an advanced dielectric material with a bulk dielectric constant below 2.5. These materials are produced through the introduction of nanometer-scale porosity into an OSG skeleton. The pore size, morphology, and interconnectivity is controlled by the choice of OSG precursor, pore former, and process conditions. During integration, liquids can be absorbed into the pore network (e.g. during the polishing and cleaning process steps, resulting in a degradation of the electrical and mechanical properties [1-3]. The objective of this paper is to evaluate the impact of the CMP and post-CMP cleaning process steps on cohesive fracture in a porous OSG dielectric and the adhesive fracture of SiCN cap with porous OSG and copper films.