| High permittivity hafnia, HfO2, and hafnium silicate, HfSiO 4, are the most promising candidates to replace oxide (SiOx) or oxynitride (SiOxNy) based gate dielectrics in future generation CMOS devices. In this thesis, the effects of processing (deposition techniques, post deposition annealing, nitridation) on nanostructure evolution (crystallization, phase segregation, interlayer growth), changes in nanochemistry (impurity content, interfacial reaction, interdiffusion, oxygen diffusion, paramagnetic charge centers) and properties (EOT, oxide charges) of atomic layer deposited (ALD) Hf-O/Hf-Si-O films on Si, with different interlayers (IL), were studied. A variety of analytical techniques including XRD, RBS, XPS, SIMS, AFM, HRTEM, STEM-EELS and EPR were used.; In general, PEALD Hf-O films deposited using metal-organic precursors showed a higher C and H and lower Cl content compared to thermal ALD films using halide based precursors. Also, as-deposited ALD films (Hf-O/IL/Si) showed the formation of Hf-O-Si bonds at the Hf-O/IL interface, with increasing tendency in the presence of a chemical oxide interlayer and upon oxygen annealing.; Upon post deposition annealing (PDA) of ALD Hf-O films up to 1000°C, m-HfO2 was the stable crystalline phase. It was observed that the chemical oxide interlayer grew significantly during PDA in oxygen, the rate of which was a f (t, T) due to oxygen diffusion. Additionally, an annealed Hf-O stack (i.e., target Hf-O thickness of 4.0 nm/1.2 nm nitrided chemical oxide interlayer/Si) showed a chemically diffused HfSiOx region (2 nm) in between pure HfO2 (2 nm) and the interlayer (1.2 nm) as a result of interdiffusion and interfacial reactions. Therefore, a three-layer capacitor model was used to determine the respective contributions to the total EOT. Moreover, to correlate the presence of defects with density of interfacial states, as-deposited ALD Hf-O/chemical oxide IL/Si stacks were shown to be EPR active at 8K, due to Pb0, Pb1 type charge centers. Upon forming gas annealing (FGA) and PDA, these charge centers became hydrogen-passivated.; Using remote plasma nitridation of an ALD Hf-O film on chemical oxide IL/Si, the Hf-O layer remained amorphous even at 1000°C and exhibited a reduced tendency towards Hf-O-Si bond formation and interlayer growth when nitrogen incorporation was ∼1.7 at % of surface Hf atoms. However, the positive fixed charge density increased and oxide trapped charge density decreased with nitrogen incorporation.; Finally, upon PDA in nitrogen at 1000°C for 10 seconds of ALD Hf-Si-O films with 60 and 75 mol % HfO2, the amorphous films transformed to t-HfO2 nano-crystallites embedded in a silica-rich amorphous matrix. However, amorphous Hf-Si-O films with 40 mol% HfO2 (i.e., silica-rich) when subjected to the same PDA, phase segregated into predominantly two amorphous phases. |
