Deposition and characterization of low temperature silicon nitride films deposited by inductively coupled plasma CVD

Silicon nitride films have been deposited at a low temperature (70 °C) by inductively coupled plasma chemical vapor deposition (ICP-CVD) technique and their physical and chemical properties were studied. For a deposited SiN sample, β-phase was observed and refractive index of 2.1 at 13.18 nm/min deposition rate was obtained. The attained stress of 0.08 GPa is lower as compared to the reported value of 1.1 GPa for SiN thin films. To study the deposited film, characterization was performed using X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), micro Raman spectroscopy, Fourier transfer infrared spectroscopy (FTIR), cross-section scanning electron microscopy (SEM) and atomic force microscopy (AFM).

Research highlights▶ Silicon nitride thin films deposited at low substrate temperature of 70 °C by ICP-CVD were found to be of β-phase having pinhole free film. ▶ The deposition rate was 13 nm/min which is more than other reported techniques. ▶ AFM showed grain size in the range 3-8 nm2 equivalent to that obtained from XRD and film RMS roughness 0.1-0.6 nm. ▶ These properties make the film a better choice for MEMS application, where low temperature, high deposition rate, low stress and better reliability structural layer is required.