Surface and optical properties of silicon nitride deposited by inductively coupled plasma-chemical vapor deposition

The surface and optical properties of silicon nitride samples with different compositions were investigated. The samples were deposited on In P by inductively coupled plasma chemical vapor deposition using different NH3 flow rates. Atomic force microscopy measurements show that the surface roughness is increased for the samples with both low and high NH3 flow rates. By optimization, when the NH3 flow rate is 6 sccm, a smooth surface with RMS roughness of 0.74 nm over a 5 × 5 μm2 area has been achieved. X-ray photoelectron spectroscopy measurements reveal the Si/N ratio of the samples as a function of NH3 flow rate. It is found that amorphous silicon is dominant in the samples with low NH3 flow rates, which is also proved in Raman measurements. The bonding energies of the Si and N atoms have been extracted and analyzed. Results show that the bonding states of Si atoms transfer from Si0 to Si+4 as the NH3 flow rate increases.