Effects of PECVD deposition fluxes on the spatial variation of thin film density of as-deposited SiO2 films in interconnect structures

Atomic force microscopy (AFM) measurements in conjunction with isotropic wet etching was utilized to extract the 2D etch rate variation of PECVD-deposited SiO₂ within aggressive structures. The etch rate, with resolution of 2.5 nm/min, was measured as a function of location within a cantilever test structure. The etch rate variation has been compared with calculated ion/neutral deposition flux distribution generated by an experimentally based deposition simulator. A model to predict film density as a function of ion flux which is based on collision induced thermal exchanges and collision induced surface diffusion is being considered