In this paper, we investigate the effect of silicon surface cleaning prior to oxidation on the reliability of ultra-thin oxides. It is demonstrated that chemical preoxide grown in H/sub 2/SO/sub 4//H/sub 2/O/sub 2/(SPM) solution prior to oxidation provides better oxide integrity than both HF-based solution dipping and preoxide grown in RCA SC1 or SC2 solutions. It is also found that the oxides with SPM preoxide exhibit better hot-carrier immunity than the RCA cleaned oxides.

Dependence of ultra-thin gate oxide reliability on surface cleaning approach

Ultrathin tunnel oxides (SiOx) were grown on silicon, pretreated with 5% hydrofluoric acid, using high pressure, low temperature oxidation. These oxides were characterized using variable illumination current-voltage (Voc - Jsc) measurements on semi-transparent metal gate MIS diodes. The open circuit voltage (Voc), short circuit current (Jsc), ideality factor (n) and reverse saturation current (Jo) are studied as a function of oxidation time. The interface state density Dits for the HF treated sample was found to decrease from 2 X 1012 cm-2eV-1 to 9.21 X 1011 cm-2eV-1. Highly reproducible, good quality ultrathin oxides were obtained by pre-treatment of the wafer in hydrofluoric acid.

E. T. P. Benny

Papers

Ultrathin oxide (SiOx) grown on HF-treated silicon