Abstract
Using a combination of copper (Cu) thermocompression bonding and silicon wafer thinning, a face-to-face silicon bi-layer layer stack is fabricated. The oxygen content in the bonded Cu layer is analyzed using secondary ion mass spectrometry (SIMS). Copper-covered wafers that are exposed to the air for 12 h and 12 days prior to bonding exhibit 0.08 at.% and 2.96 at.% of oxygen, respectively. However, prebonding forming gas anneal at 150°C for 15 min on 12-day-old Cu wafers successfully reduces the oxygen content in the bonded Cu layer to 0.52 at.%.
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Tan, C.S., Chen, K.N., Fan, A. et al. The effect of forming gas anneal on the oxygen content in bonded copper layer. J. Electron. Mater. 34, 1598–1602 (2005). https://doi.org/10.1007/s11664-005-0171-9
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DOI: https://doi.org/10.1007/s11664-005-0171-9