Suppression of MOSFET reverse short channel effect by N/sub 2/O gate poly reoxidation process

We show that an N/sub 2/O oxynitride post-gate poly reoxidation process is effective in suppressing the reverse short channel effect (RSCE). A significant reduction in RSCE (/spl sim/30%) was obtained experimentally for the N/sub 2/O reoxidation process compared to the standard O/sub 2/ thermal reoxidation. A reduced level of interstitial injection by the oxynitridation of silicon interface is believed to be responsible for counteracting the local oxidation enhanced lateral diffusion. We further identify the critical trade-offs in channel profile engineering. That is, transistors with high channel mobility suffers from more pronounced RSCE if subject to interstitial injection after the gate definition. Excellent sub-half micron CMOS device and low-voltage ring oscillator performance are demonstrated using this process.<
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