Comparative studies on the effect of Ultra-dilute RCA cleans,
chemical ratios in excess of 300:1, and Dilute RCA cleans,
chemical ratios around 50:1, on the integrity of thin gate oxides have been
performed. Ultra-dilute RCA chemistries have shown particle removal
efficiency, metallic contamination removal, surface roughness, Qbd, BVox and
defect density equivalent to those obtained using dilute RCA chemistries.
Furthermore ultra-dilute chemistries use less chemical leading to shorter
rinse times and thus increased throughput as compared to the dilute RCA