Electrical properties and structure of laser-spike-annealed hafnium oxide

We studied the effects of laser-spike annealing (LSA) on hafnium oxide high-k dielectrics using high power diode laser. The equivalent oxide thickness of HfO2 gate stacks annealed using a moderate laser power decreased noticeably as compared to as-grown films due to densification and crystallization of HfO2. Transmission electron microscope and X-ray photoelectron spectroscopy show that regrowth of interfacial oxide and silication of HfO2 layer are suppressed in case of LSA compared with rapid thermal annealing. Capacitance voltage hysteresis revealed stronger charge trapping/de-trapping behavior for LSA gate stacks as compared to rapid thermal annealed gate stack. However, bias-stress-induced flat band voltage shifts of LSA gate stacks were within acceptable levels, ≲ 30 mV, showing controllable threshold voltage.