The correlation of contaminants in a process bath with contaminants on a silicon wafer prepared in the bath is important information when developing a cleaning strategy. In this paper, we present such a correlation focused on contaminants in dilute HF (1:100) and in SC1 (1:1:5 and 1:1:80 at 50°C and 65°C). We have limited the contamination levels to between 0 and 150 ppb. We have also limited the contaminants studied to those that are most likely to be a problem (Fe, Al, Mg, Ca, Cu, Zn, and Na). The bath concentrations are measured using ICPMS and the wafer surface concentrations are measured using both VPD/TXRF and VPD/ICPMS.

We demonstrate that Fe and Ca at the levels studied do not deposit from dilute HF, while Cu deposits, showing a linear dependence on bath concentration. We also demonstrate that in the SCl bath, both concentration and temperature are important variables in the contamination of wafers for a given bath contamination level. Al and Zn contaminate wafers most strongly, with Al being the largest contributor at the higher concentration of SC1 and Zn being the largest contributor in the lower concentration. Finally, we demonstrate that a dilute HF clean can remove everything deposited in a highly contaminated SC1 bath.