Investigation of nonuniformity phenomenon in nanoscale SiO2 and high-k gate dielectrics

Abstract

We proposed the concept of effective uniform area ratio (Keff) to evaluate the nonuniformity phenomena of SiO2 and HfO2 gate dielectrics below 3 nm. Keff can be considered as an indication of gate oxide uniformity. It is found that Keff increases with the thickness of SiO2, whereas decreases with increasing effective oxide thickness for HfO2. The reason for the observed phenomena is given in this work. The electrical and reliability characteristics were examined to check the feasibility of our concept. The tendency of Keff values was reconfirmed by the uniformity of leakage current and constant field stress test. It is believed that this methodology is useful for the future oxide quality test.