Nitrogen plasma-induced HfSiON film growth from Hf nanoscale islands on SiO2/Si

Abstract

HfSiON films for high-k dielectric applications are synthesized from Hf nanoscale islands on SiO2/Si(100) substrates using the exposure of nitrogen inductively coupled plasma (ICP). The process consists of the novel interfacial reaction of nanoscale islands with the substrate induced by plasma-derived radicals and ions. The Hf metal islands nucleate on an SiO2/Si(100) surface by strain-induced engineering during electron beam evaporation. In vacuo AFM measurement shows that the N2 ICP exposure collapses the islands to form films. XPS analysis shows that the ICP exposure initially nitrides Hf islands in 1 min. Then, it induces the intermixing of the base SiO2 with HfN in the next stage. The rapid nitridation of Hf is the unique feature of the process initiated from nanoscale islands. The chemical composition ratio of Hf:Si:N in the film can be roughly controlled to be 1:1:1 with an ICP exposure time of 20 min. The uniformity of the grown films depends on the initial uniformity of the islands and the surface diffusion of materials. The study is a unique example of the film-growth method based on the nanoscale interaction of the surface of nucleated islands and the substrate material induced by plasmas.