A high speed buried channel MOSFET isolated by an implanted silicon dioxide layer

This paper reports a high speed buried channel MOSFET dielectrically, isolated from the substrate by using oxygen implantation technology. An implanted silicon dioxide layer is formed just beneath the surface. An n-type epitaxial layer is grown on the remaining thin single-crystal layer at the surface. Then, buried channel MOSFETs were formed on the n-type layer. MOSFETs with various channel lengths were fabricated. Sub-micron MOSFETs have shown much smaller threshold voltage shift, compared conventional ones, which agrees with the result of the two-dimensional numerical calculation. The ring-oscillator composed of MOSFETs with 1 µm channel length has shown a minimum delay time of 95 ps and power delay product of 310 fJ at VDDof 15 V.