Surface Electrical Charge on a Liquid-Dispensed Spinning Wafer in Single-Wafer Wet Processing

摘要

Single-wafer wet clean processing, with the advantage of cross-contamination free, low chemical/de-ionized water consumption, and high throughput, is becoming an emerging technology in semiconductor fabrication. A single-wafer wet clean tool puts spin on a wafer with chemicals/de-ionized waters dispensed from top and back to remove/rinse out particles and residues on both sides of the wafer. However, the voltage potential generated across the wafer surface when liquid is dispensed on a fast-spinning wafer has been a primary concern for possible electrical damage on device level during single-wafer wet processing. The purpose of this study is to experimentally determine the relationship of the induced wafer surface voltage potential to wafer spin rate, liquid dispense duration, liquid type, de-ionized water temperature/flow rate/oxygen content, and chemical concentration. A model was developed to conceptually interpret the wafer surface charge formation during single-wafer wet processing. Measurement criteria of wafer surface charge potential with respect to the electrical damage on wafer device level were also established in this work. This research will benefit recipe design to eliminate electrical damage in single-wafer wet processing.