Segregation and defect termination of fluorine at SiO2/Si interfaces

Segregation of fluorine in a SiO2/Si structure has been examined with respect to depth profile and paramagnetic defects at the SiO2/Si interface. The fluorine distribution was found to be restricted to a narrow (less than 35 Å) interface region on the oxide side. Furthermore, a greater amount of fluorine segregation was observed for (111) than for (100) interfaces. These observations suggest that fluorine segregation is caused by intrinsic defects in the interface region and that fluorine atoms terminate the defects. In fact, electron spin resonance measurements provide direct confirmation that fluorine atoms terminate the trivalent Si dangling bonds at the interface.