Plasma induced damage mitigation in spin-on self-assembly based ultra low-k dielectrics using template residues

摘要

This paper describes an approach for the reduction of plasma-induced damage in self-assembly based porous ultra low-k organosilica dielectrics. The concept is based on retention of the partially decomposed sacrificial organic phase (template) into the pores of the low-k film during plasma exposure. The amount of the template residues can be controlled by varying the hard-bake process time. It is shown that those residues are uniformly distributed throughout the film in the form of pore wall coatings. After plasma processing, the remaining residues are removed by means of a UV cure. Plasma damage to the underlying organosilica matrix was assessed by exposure of the differently hard-baked low-k films to fluorine-rich Ar/SF_6 plasma. The thickest coating, estimated to be around 0.4 nm, enables a nearly damage-free etch process without any carbon depletion or k-value degradation along with limited shrinkage induced by post-etch UV-curing (＜4.5%). These results highlight the efficiency of a simple and scalable route for damage-free integration of highly porous self-assembly based low-k dielectrics.