Metal Contamination Evaluation of Via-Last Cu TSV Process Using Notchless Si Etching and Wet Cleaning of the First Metal Layer

To confirm the effectiveness of the via-last through silicon via (TSV) process consisting of notchless Si etching and wet cleaning of the first metal layer, we evaluated the metal contamination caused by this process. The metal contamination generated near the TSV was investigated by measuring the reverse-bias leakage current of n+/p diodes placed near the TSV. The TSV diameter was 6 µm and the n+/p diode size was 0.6 × 2 µm. The distance between the n+/p diodes and the TSV was 1-10 µm. The notching size was controlled by the etching time. The reverse bias leakage current was small regardless of the distance between the TSV and n+/p diode when the notching size was small (