Slurry Development For Cu/Ultra Low k CMP

Abstract

Conventional CMP for Cu/Ultra-low k (k<2.4) integration faces significant technical challenges [1-2]. The majority of ULK materials are made porous to reduce the dielectric constant, while trading off on the mechanical strength [3-6]. With diminished hardness, elasticity and adhesion, the CMP process has to be “kinder and gentler”: lower down force, lower relative velocity, softer pad, and slurry with lower abrasive content [1,7]. In a word, the mechanical portion of the planarization process would be greatly reduced. To maintain the same performance, one has to rely on the chemical reactions to make Cu/ULK CMP a viable process.