In-Situ Study The Electronic Structure Of High-k Films By Synchrotron Radiation X-ray Photoelectron Spectroscopy

The high-k dielectric materials of Er₂O₃,La₂O₃,Al₂O₃,LaAlO₃ were deposited on Si substrate at 300? to make different thickness of the thin film,which were fabricated the multi-layer thin film structure of different system by the pulsed laser deposition?PLD?technique in the ultra-high vacuum.In-situ the interface structure of electronic between high dielectric layers and silicon substrate were studied under different temperature in oxygen by synchrotron radiation photoelectron spectroscopy.In the multi-layer film of Er₂O₃/Al₂O₃/Si structure,the interface structure of electronic using Al₂O₃ as the barrier layer have been investigated by X-ray photoelectron spectroscopy?XPS?.There is no change of Al 2p peak in Al₂O₃ in the low and high temperature before and after annealing,whether in the same barrier layer thickness of different annealing temperature or in the same annealing temperature of different thickness of the barrier layer.The Er 4d core level peaks come from erbium silicide,rather than that of intrinsic erbium oxide film.There is no change in silicon core level peak when the Al₂O₃ is deposited,and silicide have produced when we deposited Er₂O₃ thin film and annealing process.Under the same annealing temperature,the silicide is formed and the intensity and content of Si peaks in the silicide decreased with the increasing of the thickness of the Al₂O₃ films.The results indicate that the barrier layer plays an important role to prevent the diffusion and it suggests that the Al₂O₃ layer is stable and do not participate with Si interface in any reaction from deposition to annealing.But the Er₂O₃ thin films layer were deposited and annealing process,this layer and the diffusion silicon atoms through the barrier layer from the substrate are reacting and producing the silicate,indicate the interface between substrate and Er₂O₃ is not stable.In the multi-layer film of La₂O₃/LaAlO₃/Si structure,the interface structure of electronic using LaAl O3 as the barrier layer have been investigated by XPS.The result shows that it is no change of Al 2p peak in LaAlO₃ layer during deposition and annealing,and also the Si 2p signal peaks is not change,but that of peak becomeweak when deposited La₂O₃ layers and annealing.O 1s core level peaks come from hybridization between a variety of different oxide film layers and oxygen of reactants layers.The result shows that the interface are quite stable between Si substrate and LaAlO₃ layers and do not participate in any reaction whether deposition or annealing.In this system,the barrier layer of La AlO3 plays an important role to block the spread of the silicon,and further shows that it is not very stable between La₂O₃ layer and silicon substrate.These two kinds of structures were compared,that of thermal stability is getting better with the barrier layer thickness increasing.On the basis of the equivalent oxide thickness layer being kept constant and the physical thickness become thicker,which reduces the leakage current,and improve the stability of the device.