25 /spl Aring/ gate oxide without boron penetration for 0.25 and 0.3-/spl mu/m PMOSFETs

Very thin gate oxides are necessary for small CMOS transistors. However, one major challenge is boron penetration through the thin gate oxides in surface-channel PMOSFETs. Other difficulties include low breakdown voltage, thickness variation control, and device reliabilities. In this work, nitrogen was implanted in the substrate before growing thin gate oxides. 0.25-/spl mu/m and 0.30-/spl mu/m surface-channel PMOSFETs were then fabricated. New results on oxide properties and device characteristics are observed.