A theoretical study on initial growth mechanism of ZrO2 film using cyclopentadienyl-type precursor

The initial growth reaction of atomic layer deposition (ALD) of ZrO2 using Cp2Zr(CH3)2 (CpC5H5, cyclopentadienyl) as metal precursor on the hydroxylated silicon surface is investigated by using density functional theory (DFT). The ALD cycle is achieved through two types of ligand elimination reactions (i.e., CH4 and CpH elimination reactions). The possible reaction pathways are proposed in order to find the dominant initial reaction during the Cp2Zr(CH3)2 precursor pulse. DFT calculations show that the CH4 elimination reaction is energetically more favorable than CpH elimination reaction. As a result, the two CH3 ligands of Cp2Zr(CH3)2 may be dissociated prior to the two Cp rings during the metal precursor pulse. In addition, one CpH elimination may occurs sequentially following the first CH4 elimination reaction according to activation barrier analysis during the Cp2Zr(CH3)2 pulse. All the calculated results are in agreement with the experimental findings.