MOS-Diode Characteristics with HfO[sub 2] Gate Insulator Deposited by ECR Sputtering

A high-k gate insulator of deposited by sputtering using electron cyclotron resonance (ECR) plasma was investigated. films deposited in the metal mode, in which oxygen flow is controlled to be relatively small, provided small capacitance equivalent thickness of 1.1 nm and a gate leakage current of less than 1 mA/cm2 at 1 V. Fixed charges and traps were minimized by optimizing postannealing temperature and flow rate. The large amount of slow traps seen in low-frequency (1 kHz) capacitance-voltage measurements was effectively reduced by a low-temperature annealing at 400°C. Current-voltage measurements taken in the accumulation region suggest that Schottky emissions are dominant for the diodes. A very small barrier height was observed for the having an ultrathin film.