Thin SiO2/a-Si:H/SiO2 multilayer insulators obtained by electron cyclotron resonance chemical vapor deposition at room temperature for possible application in non-volatile memories

Abstract

In this work we present electrical and morphological characterization of thin multilayer structures, SiO2/a-Si:H/SiO2, with possible applications in non-volatile memories devices. All films were obtained by Electron Cyclotron Resonance Chemical Vapor Deposition technique at room temperature. To induce structural changes in the amorphous silicon layer, the gate stacks were subjected to high temperature furnace annealing at 800°C and 1100°C.Three-layer MOS structures were patterned by lithography and subjected to a sintering process in forming gas for 20min. The structures annealed at high temperature present a memory window in their capacitance-voltage dependencies, which means that these structures could have a possible application as gate insulators in non-volatile memory devices. The morphology of the amorphous layers was studied by atomic force microscopy and scanning electron microscopy which revealed increase of the surface roughness and modifications in the a-Si:H layer after the high temperature process.