Improvement in the Electrical Characteristics of a Fluorinated HfO2/Ge Gate Stack by Using a Nitrogen Radical Treatment

Abstract

The electrical property of the interfacial layer is improved by fluorine treatment on a HfO2/Ge metal-insulator-semiconductor (MIS) device. The thin HfO2 dielectric was prepared using a photoassisted metal-organic chemical vapor deposition (MOCVD) system. However, the fluorine was easily out-diffused after post metallization annealing (PMA) at high temperature. In this study, the post nitridation of the fluorinated HfO2/Ge gate stack was carried out by using a nitrogen (N) radical treatment at high temperature (200 ◦C) to prevent the fluorine (F) diffusion. Interface traps, such as poorly passivated dangling bonds and oxygen vacancies (V0), near the interface were passivated by co-doping of F and N. Consequently, the dielectric property of the HfO2/Ge gate stack was improved to hamper F out-diffusion. Therefore, we suggest that N radical treatment following F2-treatment is a very useful solution for improving the dielectric property of a HfO2/Ge gate stack.