Hollow Cathode Plasma-Enhanced Atomic Layer Deposition of Silicon Nitride Using Pentachlorodisilane

In this work, a novel chlorodisilane precursor, pentachlorodisilane (PCDS, HSi₂Cl₅), was investigated for the growth of silicon nitride (SiN _x) via hollow cathode plasma-enhanced atomic layer deposition (PEALD). A well-defined self-limiting growth behavior was successfully demonstrated over the growth temperature range of 270-360 °C. At identical process conditions, PCDS not only demonstrated approximately >20% higher growth per cycle than that of a commercially available chlorodisilane precursor, hexachlorodisilane (Si₂Cl₆), but also delivered a better or at least comparable film quality determined by characterizing the refractive index, wet etch rate, and density of the films. The composition of the SiN _x films grown at 360 °C using PCDS, as determined by X-ray photoelectron spectroscopy, showed low O content (∼2 at. %) and Cl content (<1 at. %; below the detection limit). Fourier transform infrared spectroscopy spectra suggested that N-H bonds were the dominant hydrogen-containing bonds in the SiN _x films without a significant amount of Si-H bonds originating from the precursor molecules. The possible surface reaction pathways of the PEALD SiN _x using PCDS on the surface terminated with amine groups (-NH₂ and -NH-) are proposed. The PEALD SiN _x films grown using PCDS also exhibited a leakage current density as low as 1-2 nA/cm² at 2 MV/cm and a breakdown electric field as high as ∼12 MV/cm.