Improved scalability of high-k gate dielectrics by using hf-aluminates

To satisfy the urgent need for suitable high-k dielectrics with scalability down to sub nm EOT, ALCVD ^TM HfO ₂ and Hf-Aluminates were studied in this work. The scalability of ALCVD HfO ₂ is limited by its high defect density and by the interface reaction with the conventional poly-Si gate process. The high defect density with thin HfO ₂ dielectrics results in the significant yield loss in the larger devices, and the interface reaction with the poly-Si gate process makes the EOT thicker. Therefore, EOT scaling of ALCVD HfO ₂ can be very challenging. In contrast, ALCVD Hf-Aluminates have moderate dielectric constant, low defect density and minimal EOT increase in the poly-Si gate process due to the Al incorporation in the bottom interfacial layer. They become attractive high-k dielectrics with enhanced scalability toward sub nm EOT application.