Effects of annealing on charge in HfO2 gate stacks

This letter presents a systematic investigation of charge in HfO2 gate stacks. Assuming that the majority of charge is associated with the stack interfaces, it is found that the charge at the HfO2/interfacial layer (IL) interface is negative while the charge at the SOL interface is positive. In general, the calculated charge densities at both interfaces are of order 10(12) cm(-2). A forming gas anneal (FGA) reduces the interface charge greatly at both interfaces. However, the FGA temperature does not have much effect on the charge density. The effects of post deposition anneal at various temperatures and under various atmospheres are also studied. Its found that a high temperature dilute oxidizing atmosphere anneal reduces the charge at both interfaces.