Effect of oxygen to argon ratio on the properties of thin SiO_x films deposited by r.f. sputtering

摘要

Energy Dispersive X-ray and X-ray Photoelec-tron (XPS) spectroscopies show that SiO_x films deposited by reactive r.f. magnetron sputtering at partial pressure ratios R between oxygen and argon in a wide range (1-0.005) have compositions close to the stoichiometric one. For these films high temperature annealing at 1,000 ℃ shifts the band in the Fourier Transform-Infrared spectrum due to the Si-O-Si stretching vibration to values typical of stoichiometric SiO_2. Further decrease of R leads to splitting of the Si 2p XPS line indicating increase of the Si content and formation of a second phase in a SiO_2 matrix. The electrical properties of test MOS structures with SiO_x gate dielectric, regarding defect density in the oxide and at the Si(Vc-Si interface, degrade with the decrease of R. High temperature annealing at 1,000 ℃ strongly improves the properties of all films regarding leakage current and properties of the interface.