SiCOI Structures. Technology and Characterization

Abstract

In this work, we present an alternative approach for the fabrication of SiCOI material based on the ion beam synthesis technique. In this process, β-SiC layers are synthesized by a multiple high dose C⁺ implantation designed to form a buried stoichiometric flat carbon profile. The structural characterization confirms the formation of β-SiC, while the micromechanical assessment confirms the ability of these layers for MEMS applications. Combining IBS with wafer bonding, high crystalline quality ion beam synthesized β-SiC layers with low residual strain, have been successfully transferred onto oxidized Si wafers, obtaining SiCOI structure with abrupt SiC/SiO₂ interfaces and low surface roughness

On the other hand, the high flexibility of IBS has allowed the fabrication of polycrystalline SiC on insulator by direct conversion of amorphous and polycrystalline Si on SiO₂ layers. The structural characterization indicates that in this case the structure of the poly-SiC layers is mainly determined by the implant temperature rather than by the topotactic transformation usually invoked in the case of crystalline materials. It is also found that when implanting pre-doped layers, the presence of interstitial P atoms leads to a significant deformation of the lattice, whereas activated P atoms in substitutional sites during the carbon implantation does not cause significant additional stress in the final poly-SiC layers, although neither does it seem to have any stress reduction effect. The micromechanical structures made from these samples suggest the viability of the direct IBS of poly-SiCOI structures for MEMS applications.