Paper TF2-TuA12
ALD of La Stabilized Amorphous HfO₂ High-k Dielectric Thin Films

Tuesday, November 10, 2009, 5:40 pm, Room B4

La₂O₃ was incorporated into hafnium dioxide grown by atomic layer deposition (ALD) to stabilize the amorphous phase during high temperature annealing. The incorporation was achieved by depositing HfO₂ and La₂O₃ alternatively in different ALD cycles. X-ray photoelectron spectroscopy compositional analysis shows that the Hf and La atomic percentage ratio can be controlled by varying the number of separate Hf and La ALD cycles. Microstructure was determined with X-ray diffraction and cross-sectional transmission electron microscopy. The introduction of La increases the film crystallization temperature from 5 00 °C for a HfO₂ film to 800 °C, 900 °C and 950 °C for 10 nm films containing 13% La (metal basis), 25% La and 43% La, respectively. Due to the ALD growth mechanism, the film is a HfO₂-HfLa_xO_y periodic structure in which La just interacts with a limited thickness of HfO₂, and La-free layers mainly composed of HfO₂. The presence of periodic HfO₂ thin interval layers adds an extra advantage in amorphous stabilization during high temperature annealing over that found for homogeneous HfLa_xO_y mixtures and less overall La is required. Therefore ALD incorporating La is a potential method to grow amorphous HfO₂-La₂O₃ high-к dielectric thin films.