Epitaxial Growth and Properties of Silicon on Crystalline Rare-Earth-Metal Oxide for SOI-Applications
Keywords:silicon on isolator, MBE, rare earth metal oxide, high-k dielectrics
Silicon on isolator technology decreases effects of parasitic capacitance and leakage between the circuit components that limit the density of transistors in the conventional bulk complementary metal oxide semiconductor field effect transistor technology. There are several methods for fabrication of SOI substrates. Additional fabrication costs for SOI substrates limit application of this technology for production of main stream chips. New technological solutions and materials are needed. Two new approaches for fabrication of silicon on isolator structure with crystalline gadolinium oxide as buried oxide are studied. The first approach is based on the formation of a template single crystalline Si-layer and combines encapsulated solid-phase epitaxy of silicon on rare-earth-metal-oxide layer (developed for fabrication of oxide/silicon/oxide heterostructures), subsequent chemical etching of the second oxide layer, followed by vapor-phase epitaxial growth of silicon on the template-silicon layer. In the second method, crystalline single oriented silicon islands serve as seed for further epitaxial growth of a crystalline Si layer on gadolinium oxide. Structural investigations show that the overgrown silicon layer is structurally coherent with the template silicon layer with no distinguishable difference at the interface. Silicon-substrate/oxide/silicon heterostructure exhibits transition of the substrate crystalline structure with A/B/A twinning relationship and in A/B/B relationship in some regions. The initial stage of deposition of the template silicon is crucial for its structural quality.
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