Effect of process temperature on the structural and electrical properties of atomic layer deposited ZrO2 films using tris(dimethylamino) cyclopentadienyl zirconium precursor

Abstract

The authors investigate the deposition of ZrO2 by atomic layer deposition (ALD) process using tris(dimethylamino) cyclopentadienyl zirconium (Cp-Zr) as a precursor, and the effect of deposition temperature on the structural and electrical properties of ZrO2 thin films are studied. The ALD process window of Cp-Zr is found at 300–350 °C, and no noticeable change in the film composition occurs within the ALD process window and the films are all stoichiometric. However, the crystallinity of the film is significantly affected by the deposition temperature. At 300 °C, only the cubic and tetragonal phases are detected, while the monoclinic peak starts to appear at 325 °C. Consequently, the highest dielectric constant (35.8) is observed for the ZrO2 films deposited at 300 °C. In contrast, ZrO2 films deposited at 350 °C show the lowest leakage current. This trend is due to the lower carbon impurity contents along with the increase in deposition temperature. To study the electrical properties of ZrO2 films in more detail, capacitance–voltage hysteresis measurements are carried out; the hysteresis is reduced abruptly with an increase in deposition temperature.