Impact of O[sub 3] Concentration on Ultrathin HfO[sub 2] Films Deposited on HF-Cleaned Silicon Using Atomic Layer Deposition with Hf[N(CH[sub 3])(C[sub 2]H[sub 5])][sub 4]

Abstract

We studied the effect of ambient concentration on the electrical properties of ultrathin gate dielectric formed by atomic layer deposition (ALD) using as a precursor. The films were intended for use in replacement metal gate transistors and were fabricated on silicon substrates that had undergone a final clean using diluted hydrofluoric acid. From the results of capacitance–voltage measurements and transmission electron microscopy images, the interfacial layer for could be made about thinner than that for . The concentration of carbon impurities was at an acceptable level in the ALD films by using the low concentration of . The measured leakage current densities for of were reduced by about 5 orders of magnitude with respect to reference films. From these results, it was judged that concentrations of were suitable for the fabrication of ultrathin gate dielectrics and would improve their electrical properties.