Towards the Fabrication of Ultra-Thin SOI on Si (001) using Epitaxial Oxide and Epitaxial Semiconductor Growth Processes

Silicon on insulator (SOI) substrates will be required to reduce capacitive coupling and other parasitic effects as device scaling continues. ITRS projections point to a future need for SOI buried oxide layers as thin as 10 nm, and Si channel thickness potentially as low as 5 nm for fully- depleted ultra-thin-body devices. For such thin layers, conventional SOI fabrication processes become increasingly difficult. Progress towards fabricating ultra-thin SOI on Si (001) through an all-growth approach is presented. All steps are performed sequentially in situ, with no wet chemical processing. Starting with a Si wafer as large as 8 , our approach is to: 1) deposit a thin commensurate epitaxial oxide layer such as Ca1-xSrxTiO3; 2) oxidize to grow an interface SiO2 layer ('floating' the epitaxial oxide) for stress relief and lowering of the dielectric constant; and 3) deposit epitaxial Si or Si1-xGex to complete the fabrication process.