| Several experimental and theoretical results relating to thin film silicon oxide and oxynitride gate dielectrics are discussed. First, I present a model for the gas-phase chemistry of N{dollar}sb2{dollar}O decomposition, a gas which is often used to grow silicon oxynitride. The growth rate and nitrogen content of these films vary with N{dollar}sb2{dollar}O gas flow rate and temperature. By measuring the NO content in the furnace exhaust gas, I show that this is due to changes in the NO/O{dollar}sb2{dollar} ratio. A quantitative model, based on available kinetic data, is developed which accounts for these effects, and agrees with my experimental measurements. The role of atomic oxygen, an intermediate species in decomposition, is also investigated.; In addition, a new model is presented for boron diffusion in silicon oxides and oxynitrides, in which boron diffuses substitutionally for silicon atoms, and the role of incorporated nitrogen is to occlude diffusion pathways. A monte carlo simulation based on this model accurately accounts for lowered diffusivities due to incorporated nitrogen, when compared to a series of experiments on pMOS-type structures. An identical mechanism appears to be responsible for phosphorous diffusion. I furthermore show that the effective diffusivity of boron decreases with anneal time. |
