Low-temperature fabrication of silicon nitride thin films from a SiH4+N2 gas mixture by controlling SiNx nanoparticle growth in multi-hollow remote plasma chemical vapor deposition

Abstract

High-quality amorphous silicon nitride (SiNx) thin films were fabricated by the controlled growth of nanoparticles during SiH4+N2 multi-hollow remote plasma chemical vapor deposition (CVD) at low substrate temperature 100 °C. Measurements from quartz crystal microbalances showed that a higher amount of nanoparticle incorporation in the SiNx film corresponded to a higher ratio of N/Si in the film, implying that the nanoparticles were nitrided in the plasma phase. We controlled the size of the nanoparticles by tuning the gas flow ratio of N2/SiH4 and the total gas flow rate. Transmission electron microscopy and energy-dispersive X-ray spectroscopy showed that smaller nanoparticles in the plasma led to a higher ratio of N/Si in the film and a lower hydrogen content. We attribute these results to the low heat capacity and large specific surface area of the nanoparticles, which enabled active chemical reactions on their surface in the plasma.