Rajesh Katamreddy, B. Feist, C. Takoudis
Aug 1, 2008
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Influential Citations
19
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Journal
Journal of The Electrochemical Society
Abstract
Bis(diethylamino) silane is studied and evaluated as a liquid-phase, silicon precursor in the low-temperature atomic layer deposition (ALD) of hafnium silicate films. The depositions were performed using ozone as the oxidizing reagent and tetrakis(diethylamino)hafnium as the source of hafnium in hafnium silicate. The ALD process temperature windows for the deposition of silicon dioxide and hafnium oxide from the aforementioned precursors overlap between 200 and 250°C. This overlap of temperature process windows is especially advantageous as it allows ALD of composite HfSiO x films. The variable compositions of HfSiO x films were prepared by varying ALD pulse sequencing, and excellent tunability of film composition is confirmed using Rutherford backscattering spectroscopy. The morphology of resulting films was also studied using X-ray diffraction. Whereas the SiO 2 films were amorphous after deposition and remained amorphous up to deposition annealing temperatures of 1000°C, the HfO 2 films were amorphous as-deposited but started crystallizing at annealing temperatures above 600°C. The amorphous structure stability in ternary films of HfSiO x was found to depend on the relative amounts of hafnia and silica deposited. For example, films prepared by alternating five cycles of hafnia and one cycle of silica remained amorphous up to 800°C annealing, while films prepared by less than 2:1 alternating hafnia:silica cycles remained amorphous up to 1000°C.