AVS 50th International Symposium
    High-k Gate Dielectrics and Devices Topical Conference Tuesday Sessions
       Session DI-TuP

Paper DI-TuP3
Thermal Stability of Al- and Zr- doped HfO@sub 2@ Thin Films by DC Magnetron Sputtering

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: Y.E. Hong, Yonsei University, South Korea
Authors: Y.E. Hong, Yonsei University, South Korea
Y.S. Kim, Yonsei University, South Korea
D.H. Ko, Yonsei University, South Korea
D.W. Lee, Yonsei University, South Korea
J.-H. Ku, Samsung Electronics, South Korea
Correspondent: Click to Email
Currently, high-k materials are under consideration as replacements for SiO@sub 2@ because physically thick film with high dielectric constant is possible solution for reducing leakage current. Among some metal oxides such as Al@sub 2@O@sub 3@, ZrO@sub 2@, and HfO@sub 2@, particularly HfO@sub 2@ exhibits excellent material properties such as high permittivity of up to 30, energy gap of 5.6eV and thermal stability in contact with silicon. However, after post-deposition annealing above 400°C, as-deposited amorphous HfO@sub 2@ crystallizes which may induce grain boundary leakage current. In addition, annealing in an oxygen rich ambient leads to fast diffusion of oxygen through the HfO@sub 2@, resulting in the growth of uncontrollable interfacial layer between HfO@sub 2@ and silicon substrate. In this study, we investigated comparatively the thermal stability properties of HfO@sub 2@ based films with Al- and Zr-doping. HfO@sub 2@ was prepared by sputtering Hf target in a mixture of oxygen and argon at room temperature. Al- and Zr-doping is achieved by co-sputtering using Al and Zr target. And the compositions of the doped films were controlled by target power. After the formation of the films, annealing at 500~900°C for 5min by furnace in N@sub 2@ ambient was followed. The compositions and the chemical states of the oxide films were confirmed by RBS and XPS. The crystallization temperature of the HfO@sub 2@ film which has 10% Al was 900°C. However, most of the Zr-doped HfO@sub 2@ films were crystallized from as deposited condition. As an annealing temperature increases, HRTEM analyses of the all doped films show the increased interfacial layer thickness, and the interfacial layer of the Zr-doped HfO@sub 2@ films is thicker than the Al-doped. The increased CET and leakage current values through CV/IV measurements and dielectric constant difference between Al- and Hf-doped HfO@sub 2@ films will be presented and discussed.