Morphology and Growth Mechanism of Zirconium Oxide High-k Dielectric Films

Thin films of zirconium oxide were deposited on Si(100)substrates by reactive radio frequency magnetron sputtering.The films were characterized by high-resolution transmission electron microscope(HRTEM)and atomic force microscope(AFM)to investigate the variation of surface mor- phology and microstructure with oxygen partial pressures and deposition temperatures,respectively. With the increase in oxygen partial pressure ratio from 7% to 100%,the surface roughness approxi- matively linearly increases,and the phase transition of the films is a-ZrO_2(amorphous)→a-ZrO_2 with a little m-ZrO_2(monoclinic)→m-ZrO_2+t-ZrO_2(tetragonal)→m-ZrO_2.For deposition temperatures ranging from room temperature to 550℃,the phase transition of the films is a-ZrO_2(below 250℃)→m- ZrO_2 with a little a-ZrO_2(450℃)→m-ZrO_2 with a little t-ZrO_2(550℃).According to the results on the structure and surface morphology of ZrO_2 thin films,the dependence of deposition temperature on surface evolution and its physical mechanism are discussed also.