FIRST PRINCIPLE MOLECULAR DYNAMIC SIMULATIONS OF OXYGEN PLASMA ETCHING OF ORGANOSILICATE LOW DIELECTRIC MATERIALS

摘要

Plasma/surface interaction plays an important role in material processing. In the microelectronic processing, plasma etching is used to selectively remove layers of dielectric or photo resist. Atomic simulations can provide detailed mechanistic understanding of plasma/surface interactions that are usually difficult to obtain in other theoretical or experimental methods. In this work, we use Density functional Theory based first principle molecular dynamics (AIMD) simulations to investigate atmospheric etching of organosilicate low dielectric materials by using model structure for the low dielectric materials. It is found that threshold energies and reaction products strongly depend on the incident angles of (~3P) atomic oxygen and target atom. The lowest threshold energy for reaction for carbon removal is found to be 0.1 eV when atomic oxygen attacks silicon in a direction inclined to the Si-C bond. The reaction produces a methyl radical leaving the molecule, hence a carbon removal mechanism, and forms a Si-0 bond. The simulation results agree well with experimental results and support diffusion controlled etching rate dependence and dielectric constant increases due to etching.