A SIMPLE APPROACH TO REDUCE INTERLAYER FORMATION OF SPUTTERED HF-BASED GATE DIELECTRICS BY NITROGEN INCORPORATION

摘要

In this work, we have demonstrated a simple approach to suppress interfacial layer (IL) formation for HfO_x and HfO_xN_y gate dielectrics by sputtering HID, and HfN_x films, respectively, followed by further annealing. The material characteristics of dielectric films were investigated by glancing incident angle X-ray diffraction (GIAXRD), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry. Both HfO, and HfO_xN_y films show amorphous structures after annealing up to 700 °C; nevertheless, the HfO_xN_y film presents the superiority to prevent interfacial layer (IL) formation over the HfO_x, film. Formation of a self-doped nitrogen-contained IL in the HfO_xN_y dielectric stack is detected by XPS analysis. Furthermore, the HfO_xN_y dielectric layer presents higher refractive index (about 2.0) than that of HID, (about 1.8) in the range of visible light, indicative of its denser structure. It is suggested that a high nitrogen-doped HfO_xN_y dielectric stack can be achieved by this method, showing better properties than the HID, one.