Annealing behavior of atomic layer deposited hafnium oxide on silicon: Changes at the interface

Abstract

Thin films of hafnium oxide are deposited on Si(100) substrates by means of atomic layer deposition using tetrakis(diethylamino)hafnium and water on Si(100) at 300°C. Detailed studies of temperature induced annealing effects on the HfO2∕Si interface are done using angle resolved x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and time of flight secondary ion mass spectroscopy (ToF-SIMS). As-deposited films show mostly native silicon oxide at the interface. Crystallization of HfO2 film initiates at about 600°C. As the annealing temperature is increased, the hafnium silicate content in the film is found to increase and the mostly silicon oxide interlayer is found to grow thicker under Ar atmosphere. Also, the formation of hafnium silicide is found to take place at temperatures ⩾800°C. The XPS data shows decomposition of the interfacial hafnium silicate layer into hafnium oxide and silicon oxide at 1000°C along with increasing formation of hafnium silicide. The ToF-SIMS data suggest interdiffusion of the hafnium oxide film and the interfacial silicon oxide during the annealing process.