Cost-effective cleaning and high-quality thin gate oxides

Some recent findings in the area of wafer cleaning and thin oxide propertie s are presented in this paper. Results are shown for a practical implementa tion of a simplified cleaning concept that combines excellent performance i n terms of metal and particle removal with low chemical and DI-water consum ption. The effect of organic contamination on ultrathin gate-oxide integrit y is illustrated, and the feasibility of using ozonated DI water as an orga nic removal step is discussed. Metal outplating from HF and HF/HCl solution s is investigated. Also, the final rinsing step is critically evaluated. It is demonstrated that Si surface roughness without the presence of metal co ntaminants does not degrade gate-oxide integrity. Finally, some critical re marks on the reliability measurements for ultrathin gate oxides are given; it is shown that erroneous conclusions Can be drawn from constant-current c harge-to-breakdown measurements.