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 dimethylaminomethylsilyl or trimethylsilyl groups to obtain sufficient thermal stability. The silylamine compounds 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 N2 plasma. The PEALD process window was between 250 and 400 °C with a growth rate of 0.36 Å/cycle. The best film quality was obtained at 400 °C with a RF power of 100 W. The PEALD film prepared showed good bottom and sidewall coverages of ∼80% and ∼73%, respectively, on a trench-patterned wafer with an aspect ratio of 5.5.

The reactivity of surface sites plays a very important role to determine the thermodynamics and kinetics of ALD processes.

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We report the catalyzed atomic layer deposition (ALD) of silicon oxide using SiCl, HO, and various alkylamines. The density functional theory (DFT) calculations using the periodic slab model of the SiO surface were performed for the selection of alternative Lewis base catalysts with high catalytic activities. During the first half-reaction, the catalysts with less steric hindrance such as pyridine would be more effective than bulky alkylamines despite lower nucleophilicity. On the other hand, during the second half-reaction, the catalysts with a high nucleophilicity such as triethylamine (EtN) would be more efficient because the steric hindrance is less critical. The in situ process monitoring shows that the calculated atomic charge is a good indicator for expecting the catalyst activity in the ALD reaction. The use of EtN in the second half-reaction was essential to improving the growth rate as well as the step coverage of the film because the EtN-catalyzed process deposited a SiO film with a step coverage of 98% that is better than 93% of the pyridine-catalyzed process. The adsorption of pyridine, ammonia (NH), or trimethylamine (MeN) salts was more favorable than that of EtN, n-PrN, or PrN salts. Therefore, EtN was expected to incorporate less amine salts in the film as compared to pyridine, and the compositional analyses confirmed that the concentrations of Cl and N by the EtN-catalyzed process were significantly lower than those by the pyridine-catalyzed process.

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