Composition dependence of interface control and optimization on the performance of an HfTiON gate dielectric metal-oxide-semiconductor capacitor

Composition dependence of interface control, band alignment and electrical properties of HfTiON/Si grown by sputtering has been studied by spectroscopy ellipsometry (SE), x-ray photoelectron spectroscopy (XPS) and electrical measurement. Analysis from XPS has confirmed that the interfacial layer consisting of silicate and SiO(x) is formed unavoidably, irrespective of composition ratio. Meanwhile, reduction in band gap and asymmetric band alignment has been detected for HfTiON films with the increase in Ti composition. To meet the requirements of high-k dielectrics with the barrier height of over 1 eV, the incorporation composition ratio needs to be carefully optimized. As a result, improved C-V characteristics and reduced leakage current have been achieved from HfTiON gate dielectric MOS capacitors with optimized composition ratio of Hf:Ti = 1:1, which can be attributed to the reduction in oxygen-related traps and the obtained near-symmetric band alignment relative to Si.