Plasma-Enhanced Atomic Layer Deposition of Silicon Nitride Using a Novel Silylamine Precursor

We report the plasma-enhanced atomic layer deposition (PEALD) of silicon nitride thin film using a silylamine compound as the silicon precursor. A series of silylamine compounds were designed by replacing SiH3 groups in trisilylamine by dimethylaminome-thylsilyl or trimethylsilyl groups to obtain sufficient thermal stability. The silylamine compound's were synthesized through redistribution, amino-substitution, lithiation, and silylation reactions. Among them, bis(dimethylaminomethylsilyl)trimethylsilyl amine (C9H29N3Si3, DTDN2-H2) was selected as the silicon precursor because of the lowest bond,dissociation energy and sufficient vapor pressures. The energies for adsorption and reaction of DTDN2-H2 with the silicon nitride surface were also calculated by density functional theory. PEALD silicon nitride thin films were prepared using DTDN2-H2 and N-2 plasma. The PEALD process window was between 250 and 400 degrees C with a growth rate of 0.36 angstrom/cycle. The best film quality was obtained at 400 degrees C with a RF power of 100 W. The PEALD film prepared showed good bottom and sidewall. coverages of similar to 80% and similar to 73%, respectively, on a trench-patterned wafer with an aspect ratio, of 5.5.