Low-frequency noise characteristics of HfSiON gate-dielectric metal-oxide-semiconductor-field-effect transistors

High dielectric constant materials are being developed as possible replacements for SiO2 as the gate dielectric. Although these materials do overcome the issue of gate leakage current because of increased thickness for a given equivalent capacitance, several other problems arise, such as degraded carrier mobility and higher low-frequency noise due to increased fixed charges and traps in the high-k film. HfSiON gate-dielectric metal-oxide-semiconductor field-effect transistors (MOSFETs), presented here, offer lower 1∕f noise compared to other high-k materials, but the noise levels are relatively higher than in SiO2 devices. Oxide-trap-induced correlated carrier number-mobility fluctuations dominate in all of these devices. Measured noise characteristics as well as extracted oxide trap density values are discussed for various geometries and sizes. The latter, measured to be 1.5×1019–1.6×1020cm−3eV−1, is higher than that for SiO2 MOSFETs with similar dimensions (4.1×1016–7.8×1016cm−3eV−1). This work represents an investigation of interface generated flicker noise on HfSiON gate stacks.