Experimental determination of the temperature dependence of argon annealed fixed oxide charge at the Si/SiO2 interface

Fixed oxide charge density Nf at the Si/SiO2 interface for (100) and (111) wafers oxidized in dry O2 and annealed in argon has been studied as a function of the Ar anneal temperature. In contrast to previous qualitative results, the annealed Nf value was found to be dependent on the anneal temperature. Wafers thermally cycled in Ar between different temperatures showed reproducible, steady state Nf values which also cycled with temperature. These results may indicate that residual charge densities after annealing represent an equilibrium state of the Si/SiO2 interface.