PDF《Microelectronics Reliability》

500 °C thermal annealing, and the thickness of the ?lms deposited at

200 °C decreases about 0.6 nm after

700 °C thermal annealing. At lower deposition temperature, there is not enough thermal energy for surface reactions, and some by-prod- ucts or intermediates are generated in the layers. As a result, the decomposition and re-composition of by-products take place dur- ing the thermal annealing, which causes the decrease of the thick- ness. However, the thickness of ?lm deposited at

300 °C increase slightly after the thermal annealing process. 3.1.2. Composition of HfO2 ?lms The physical mechanism of H2O-based ALD HfO2 is clear. How- ever, the reaction mechanism of O3-based ALD HfO2 is complicated due to the strong oxidization and lability of O3. During the deposi- tion process, O3 can split the NCC bond and CCH bonds of by-prod- ucts and ligands that are still attached to Hf. Different by-products can be formed in the HfO2 ?lms at different deposition tempera- ture. The unstable by-products can be decomposed or re-compos- ited, and the ?nal by-products can be CO2, H2O, CH2O, and NO2/NO, etc. [9C11]. As some nitrogen oxides are the strong oxidants, par- ticularly in NO2 (or its dimer N2O4) and N2O. They can participate in the ALD reactions. Meanwhile, NOx can de........