Single-wafer furnace RTCVD for silicon oxide, nitride, and oxynitride thin films

We have developed single-wafer RTP modules for LPCVD of silicon nitride, oxynitride, oxide, and oxide/nitride/oxide (ONO) composite films. All films were deposited from dichlorosilane (DCS) as a silicon source gas. The deposition of 20-40 Å silicon nitride films from DCS and NH₃ showed excellent thickness uniformity. Continuous 10-wafer runs at 735°C resulted in 40 Å Si₃N₄ films with within-wafer uniformity below 0.55% (1σ) and wafer-to-wafer uniformity of 0.50% (1σ). Conformal coverage of nitride over non-planar substrates was also demonstrated. The hot-wall reactor configuration suppresses the condensation of NH₄Cl solid byproduct. An activation energy of 1.49 eV was derived from the depositions at a reactor pressure of 0.5 Torr and DCS:NH₃ =1:3. Oxynitride films were deposited from DCS/NH₃/N₂O at 800°C. A film composition of SiO_0.6N_1.1 with a refractive index of 1.80 was obtained. Silicon dioxide (high temperature oxide, HTO) films can also be grown at 800°C from DCS and N₂O. ONO stack films of 170 Å were deposited in-situ at 800°C using sequential depositions of HTO/nitride/HTO. An Auger electron spectroscopy depth profile of the film revealed a sandwich structure of the film composition.