Highly-reliable gate oxide formation for giga-scale LSIs by using closed wet cleaning system and wet oxidation with ultra-dry unloading

We controlled the Si surface just before the oxidation process and the moisture during oxide formation to improve gate oxide quality. This was done with a closed wet cleaning (CWC) system and load-lock oxidation system. We found that wet oxidation with ultra-dry unloading (WODU) combined with pre-cleaning in a CWC system resulted in a highly-reliable gate oxide. The predicted reliability of the gate oxide formed using these techniques improved significantly, showing that a 90% yield is expected after ten years of operation, even when the total gate area is more than 1 cm/sup 2/ and the electric field is as high as 5 MV/cm, which is sufficient for giga-scale ULSIs.