Influences of rapid thermal annealing on the characteristics of Al₂O₃\La₂O₃\Si and La₂O₃\Al₂O₃\Si films deposited by atomic layer deposition

A comparative study of different sequences of two metal precursors [trimethylaluminum (TMA) and Tris(isopropylcyclopentadienyl) lanthanum (La(ⁱPrCp)₃)] for atomic layer deposition (ALD) lanthanum aluminum oxide (La₂O₃/Al₂O₃/Si) films is carried out. The percentage compositions of C and N impurity of La₂O₃/Al₂O₃/Si and Al₂O₃/La₂O₃/Si films were investigated using in situ X-ray photoelectron spectroscopy (XPS). The preliminary testing results indicate that the impurity level of films grown with different sequences before and after annealing can be well controlled. The effects of different deposition sequences on the electrical characteristics and physical properties of La₂O₃/Al₂O₃/Si and Al₂O₃/La₂O₃/Si films before and after annealing are studied by atomic force microscopy (AFM) and C–V curves. Analysis indicates the rapid thermal annealing (RTA) has significant effects on the surface roughness, equivalent oxide thickness (EOT), dielectric constant, electrical properties, and stability of different sequences of films. Additional the change of chemical bond types of RTA effects on the properties of La₂O₃/Al₂O₃/Si and Al₂O₃/La₂O₃/Si films are also investigated by XPS.