Comparative study on the use of novel heteroleptic cyclopentadienyl-based zirconium precursors with H2O and O3 for atomic layer deposition of ZrO2

Abstract

Three heteroleptic Zr precursors were studied for atomic layer deposition (ALD) of ZrO2. Films were deposited from Zr(Cp)(tBuDAD)(OiPr), Zr(MeCp)(TMEA), and Zr(Me5Cp)(TEA) with either water or ozone as the oxygen source {tBuDAD = N,N-bis(tertbutyl)ethene-1,2-diaminato, TMEA = tris[2-(methylamino)ethyl]aminate, TEA = triethoanolaminate}. Self-limiting film growth was confirmed for the Zr(Cp)(tBuDAD)(OiPr)/O3 process at 250 °C and for the Zr(Me5Cp)(TEA)/O3 process at 375 °C, which is among the highest temperatures for advanced heteroleptic precursors. Excellent film purity with C, H, and N levels below the detection limit of the elastic recoil detection analysis was obtained with ozone as the oxygen source. All the studied processes showed the same trend that at low deposition temperatures films were tetragonal ZrO2 and at higher temperatures mixtures of tetragonal and monoclinic ZrO2. With water, the monoclinic phase appeared at higher temperatures than with ozone. In addition to the deposition temperature, the film thickness affected the phase; thinner films favored the tetragonal phase and monoclinic peaks were more clearly seen in thicker films. The high thermal stability and excellent film purity show that from the three studied Zr precursors, Zr(Me5Cp)(TEA) is a noteworthy precursor candidate for ALD of ZrO2.