AbstractThe first demonstration of n-MOSFETs fabricated using strained Si1-yCy surface channels is reported. Tensile-strained Si1-yCy layers with substitutional carbon contents up to 0.8 atomic percent were epitaxially grown on <100> Si substrates by rapid thermal chemical vapor deposition, using silane and methylsilane as the silicon and carbon precursors. n-MOSFETS were fabricated using standard MOS processing with reduced thermal exposure to minimize the possibility of strain relaxation. A remote plasma CVD oxide was employed to form the gate oxide. The Si1-yCy devices exhibit electrical characteristics that are typical for Si n-MOSFETs, with good turn-on and subthreshold characteristics. MOS capacitance-voltage analysis demonstrates comparable oxide interface qualities for the Si1-yCy and Si control devices. No carbon-related leakage current is observed in source and drain diode junctions. Characterization of the MOSFET electron inversion layer mobility at room temperature shows comparable mobilities, within the sensitivity of the measurement, for the Si1-yCy and Si control devices. This is in contrast to the mobility enhancement observed in n-MOSFETs fabricated using tensile- strained Si grown on relaxed Si1-xGex layers. At low temperatures, the inversion layer mobility of Si1-yCy devices is lower than that of the Si controls, and appears to be affected by Coulomb and possibly random alloy scattering.
Strain Relaxation and Induced Defects in SiGe Thin Films Grown on Ion-Implanted Si Substrates
