Investigation of Optical, Electrical, and Mechanical Properties of MOCVD‐grown ZrO2 Films

Abstract

Metal‐organic (MO)CVD of ZrO2 thin films is performed using the precursor [Zr(NMe2)2(guan)2] (guan = η2‐(iPrN)2CNMe2) as the Zr source, together with oxygen. Film deposition is carried out on both Si(100) and glass substrates at various deposition temperatures. The resulting films are characterized by X‐ray diffraction (XRD) and atomic force microscopy (AFM) for investigating the crystallinity and morphology, respectively. Optical properties are measured by ellipsometry and UV‐vis on Si substrates and glass substrates, respectively, showing a high average refractive index of 2.14 and transmittance of more than 80% in visible light for the film deposited at 500°C. The potential of ZrO2 thin films as gate dielectrics is verified by carrying out capacitance‐voltage (C‐V) and current‐voltage (I‐V) measurements. Dielectric constants are estimated from the accumulation capacitance, and found to be in the range 12 ‐ 19 at an AC frequency of 1 MHz, and a leakage current of the order of 10−6 A cm−2 at the applied field of 1 to 2 MV cm−1 is measured for the films deposited at temperatures from 500 to 700°C. The low leakage current and high dielectric constant implies the good quality of the film, relevant for high‐k applications. The hardness of the film ranges from 4.2 to 6.3 GPa for the 400 nm thick film, as determined by nano‐indentation measurements. The optimum dielectric and hardness is found for the film deposited at 600°C, while the highest refractive index is found to be 2.14 for the film deposited at 500°C, due to higher density of the layers.