Surface Morphology of Single and Multi-Layer Silicon Nitride Dielectric Nano-Coatings on Silicon Dioxide and Polycrystalline Silicon

Abstract

Silicon nitride (Si₃N₄) in a form of single and multi-layer nanofilms is proposed to be used as a dielectric layer in nanocapacitors for operation in harsh environmental conditions. Characterization of surface morphology, roughness and chemical bonds of the Si₃N₄ coatings has an important role in production process as the surface morphology affects the contact surface with other components of the produced device. Si₃N₄ was synthesized by using low pressure chemical vapour deposition method and depositing single and multi-layer (3 – 5 layers) nanofilms on SiO₂ and polycrystalline silicon (PolySi). The total thickness of the synthesized nanofilms was 20 – 60 nm. Surface morphology was investigated by means of scanning electron microscopy (SEM) and atomic force microscopy (AFM). Chemical bonds in the layers were identified by means of Fourier transform infrared spectrometry, attenuated total reflection (FTIR-ATR) method. (From the SEM and AFM images it was estimated that both single and multi-layer coatings are deposited homogenously. Si-N breathing and stretching modes are observed in FTIR spectra and the surface morphology is highly dependent on PolySi, therefore suggesting the decrease of the roughness of the bottom electrode for use in the nanocapacitors.