Analysis of HfO2 Charge Trapping Layer Characteristics After UV Treatment

Abstract

The improvement in the charge storage characteristics in a non-volatile memory (NVM) device employing an ultraviolet (UV)-treated hafnium oxide (HfO2) layer as the charge-trapping layer is reported. X-ray photoelectron spectroscopy analysis was performed to characterize the Hf 4f and O 1s peaks. The defect densities corresponding to Hf and O after short-term UV treatment are 24.74% and 14.16%, respectively. The electrical characteristics, such as the interface trap density (Dit), dielectric constant, and flat band voltage (VFB), of single HfO2 thin films were determined via capacitance vs voltage (C–V) measurements of the fabricated metal–oxide–semiconductor (MOS) capacitors. Notably, this memory device has a maximum ΔVth of 4.10 V at 15 V, which corresponds to a 33.4% improvement in memory storage characteristics compared to those of an as-deposited HfO2 thin film-based memory. In addition, the charge retention after 10 years is 80.22%, which is superior to that of the as-deposited case. These results demonstrate the possibility of realizing high-efficiency TFT NVM devices using high-K materials, and are expected to enable further research on semiconductor devices using high-K materials as well as next-generation memory semiconductors using UV treatment.