Enhancement of Conformality of Silicon Nitride Thin Films by ABC‐Type Atomic Layer Deposition

Abstract

AbstractAtomic layer deposition (ALD) is utilized for the fabrication of miniaturized electronic devices with nanometer‐scale features. However, the conventional ALD process on high‐aspect‐ratio (HAR) substrates often results in the deposition of thin films with suboptimal conformality over the depth of the trench structures. This study introduces an ABC‐type ALD of silicon nitride (SiNx) employing vapor‐deliverable tert‐butyl chloride (TBC) as a surface inhibitor. Herein, density functional theory (DFT) calculations elucidate the surface reaction mechanisms, confirming the inhibition of the Si precursor by the t‐butyl moiety. Notably, the ABC‐type ALD exhibits reduced growth per cycle relative to the conventional process while avoiding detectable carbon contamination in the SiNx thin films. Applying this process to substrates with trench structures revealed a substantial improvement in conformality following the introduction of TBC. Furthermore, the step coverage of the deposited SiNx can be modulated by adjusting TBC exposure, enabling greater film thickness at the bottom than that at the top of the trench. The proposed method of modulating ALD processes holds potential for the high‐volume manufacturing of semiconductor devices with HAR structures.