Thermal Stability and Electrical Properties of High-k Gate Dielectric Materials

The use of SiO₂ thin films as the gate dielectric is quickly reaching a limitation due to the rapid increase in tunneling current and worsened device reliability. A logical alternative is to use a gate insulator with a higher relative dielectric constant (high-k) than silicon dioxide (3.9), thereby spurring tremendous research activities to produce better high-k gate dielectric materials. In this paper, the recent progress made in our laboratory on the high-k materials is described. The various means to improve the thermal stability of high-k materials like Ta₂O₅, ZrO₂, and HfO₂ deposited on Si and their electrical properties will be discussed. The characteristics of Al₂ O₃ gate dielectrics on fully-depleted SiGe-on-insulator (SGOI) will also be described