A chemical approach to atomic layer deposition (ALD) of oxide thin films is reported here. Instead of using water or other compounds for an oxygen source, oxygen is obtained from a metal alkoxide, which serves as both an oxygen and a metal source when it reacts with another metal compound such as a metal chloride or a metal alkyl. These reactions generally enable deposition of oxides of many metals. With this approach, an alumina film has been deposited on silicon without creating an interfacial silicon oxide layer that otherwise forms easily. This finding adds to the other benefits of the ALD method, especially the atomic-level thickness control and excellent uniformity, and takes a major step toward the scientifically challenging and technologically important task of replacing silica as the gate dielectric in the future generations of metal oxide semiconductor field effect transistors.
Dielectric thin films applicable, for instance, as insulating layers in electroluminescent display devices have been studied. In order to improve dielectric characteristics HfO2–Ta2O5 nanolaminates were prepared by atomic layer epitaxy at 325 °C. The nanolaminates were evaluated in capacitance and current–voltage measurements. By optimizing the layer thicknesses in the nanolaminate structures the dielectric properties, especially leakage current densities, could be tailored remarkably. The best nanolaminates showed charge storage factors improved up to 8 times when compared with those of the single oxide films. The presence of nanosize crystallites of monoclinic and metastable tetragonal HfO2 was observed by x‐ray diffraction analysis.