Pressure Responsive Multi-Layered Composite Nanoparticles for through Silicon Via (TSV) Chemical Mechanical Planarization (CMP) Applications

Abstract

Through silicon vias (TSV) have gained much attention due to the emergence of the vertical alignment necessary to produce 3D integrated circuit devices. Due to the large overburden caused by the electroplating process in TSV, high removal rate of copper (Cu) is essential for producing highly planar and defect free substrates. Therefore, focus has shifted to the development of processes and chemistries that produce highly planar and defect free Cu surfaces. In order to obtain this planarity, a process known as chemical mechanical planarization (CMP) is implemented in which a silica nanoparticle dispersion coupled with a mechanical force synergistically removes excess topography. The demands on TSV CMP have become stringent in order to meet the following criteria: very high removal rates, low dishing, high selectivity to nitride after barrier clear, low defectivity, and uniform surface topography. This work focuses on the development of a pressure responsive, multi-layer composite nanoparticle to provide a process driven synergy with the slurry formulation. These composites can be held together either covalently or non-covalently to the nanoparticle core using additives with amine, amino acid, and surfactant functionalities. The additives respond to an applied force and shear at the slurry-pad interface, resulting in controlled release of the slurry chemistry. Initial results show that at downforces ranging between 2.5-5 psi removal rates are at an excess of 1 micron per minute, while at below 1 psi removal rates are below 0.2 micron per minute and produce uniform surface quality at low surface roughness.