Atomic layer deposition of high-k thin films for gate and capacitor dielectrics

Atomic layer deposition (ALD) has gained acceptance as a thin film deposition technique in the semiconductor device manufacturing due to the stringent requirements of thickness uniformity, thermal budget, and step coverage over aggressive advanced IC device structures. We have developed unique ALD processes to deposit multi-component thin films such as HfSiO_x for high-k gate dielectric applications by co-injection of Hf and Si precursors. This process enables the formation of homogeneous single-layer hafnium silicate films as deposited. In contrast, the commonly used nanolaminate technique (i.e., an alternating stack of HfO₂ and SiO₂ layers) requires high temperature post-deposition annealing to interdiffuse the HfO₂ and SiO₂ to form a hafnium silicate film. We have also developed an Al₂O₃ batch ALD process on 300mm. Si (100) substrates using a multiwafer hot-wall reactor. Deposition of Al₂O₃ thin films from trimethylaluminum and ozone was accomplished using a 50-wafer batch system. For 4.6 nm thick Al₂O₃, excellent film thickness uniformity with a within-wafer (WIW) non-uniformity of <1.0% 1σ and a wafer to wafer (WTW) thickness non-uniformity of less than ±1.0% was achieved over a full batch.