Electron and hole mobility enhancements in sub-10 nm-thick strained silicon directly on insulator fabricated by a bond and etch-back technique

Electron and hole mobility enhancements are studied in Ge-free strained silicon directly on insulator fabricated by a bond and etch-back technique, for the first time. For inversion charge densities of 10/sup 13/ cm/sup -2/, electron and hole mobility enhancements of 100% (n-MOSFET, 30% effective Ge content, 15 nm-thick) and 50% (p-MOSFET, 40% effective Ge, 6 nm-thick), respectively are measured in fully depleted strained Si. For a biaxial strain level of 1.25% (30% effective Ge), hole mobility is the same for body thicknesses of 25 and 13 nm, and drops by no more than 5% for a body thickness of 8.5 nm. There is no evidence of strain relaxation, despite a generous thermal budget.