Subfemtojoule deep submicrometer-gate CMOS built in ultra-thin Si film on SIMOX substrates

A deep submicrometer gate MOSFET with fully depleted channel was fabricated using ultrathin Si film on SIMOX (separation by implanted oxygen) substrates. Ultrathin films with thicknesses down to 30 nm are shown to be effective in reduction of the short-channel effect. Thus, deep submicrometer gate MOSFETs with steep subthreshold slopes and threshold voltages insensitive to drain voltage were realized. The propagation delay of a CMOS inverter on an ultrathin SIMOX substrate was measured by a 51-stage ring oscillator configuration, with a 0.25-μm gate built in 100-nm-thickness Si film. The delay was 21.5 ps per gate at room temperature for a supply voltage of 2.5 V. With 30-nm Si film, the CMOS ring oscillators demonstrated a power-delay product of 0.5 fJ for a supply voltage of 1.5 V, also at room temperature