Very high frequency plasma CVD of silicon oxide

Different principal types of plasma-enhanced chemical vapour deposition (PECVD) processes of silicon oxides are used: the conventional RF (13.56 MHz) PECVD, remote PECVD, inductive coupled high density plasma CVD and very high frequency (VHF) PECVD. Single-wafer chambers with parallel-plate PECVD systems are expected to be the mainstream for the future for PECVD processes. Equipment and process improvements include activities to improve wafer throughput and film uniformity and to eliminate plasma damage to layers and devices. sing the excitation frequency from the commonly used 13.56 MHz up to the lower VHF range (40–80 MHz) has demonstrated higher deposition rates with good electronic film properties. le-wafer parallel-plate PECVD system was developed using a 40.68 MHz excitation. The wafer temperature is controlled by a helium back side flush avoiding also a deposition at the wafer back side. A stable plasma confined between the electrodes away from the walls of the chamber, an optimised plasma density to get a sufficient deposition rate and good film uniformity, and a controlled wafer temperature which influences the plasma–surface interaction were achieved. Using a SiH4/N2O process and a deposition rate of 1 nm/s a high breakdown voltage ≥ 6 MV/cm and a refractive index of 1.46 ± 0.015 were obtained. Film thickness uniformity was < 5%. A SF6/O2 process is used for the reactor cleaning with etching rates of about 1 nm/s.