Investigating physical and chemical changes in high-k gate stacks using nanoanalytical electron microscopy

The thermal budget involved in processing high-k gate stacks can cause undesirable physical and chemical changes which limit device performance. The transmission electron microscope and associated analytical techniques provide a way of investigating these changes on a sub-nanometre scale. Using electron energy loss near edge structure (ELNES), information on the local chemistry may be extracted. These techniques are applied to high-k dielectric stacks grown on Si and containing HfO2 and HfSiO layers.