Abstract

Previously, we have reported the low thermal expansion copper electrodeposited in solution containing 2-Mercapto-5-benzimidazolesulfonic acid sodium salt dihydrate (2M5S). In this research, we investigated the electrochemical behavior 2M5S additive by CVS and LSV measurements. The 2M5S additive showed an inhibition effect during electrodeposition of copper, both in the absence and presence of Cl−. Using a combination of the 2M5S leveler with another SDDACC leveler and SPS accelerator, the thermal expansion of copper was reduced and the TSV was filled without defects. The SEM results showed that the copper pumping height of low TEC copper in PECVD SiO2 TSV was only 0.5 μm. Meanwhile, the copper pumping height of reference conventional copper in PECVD SiO2 TSV was about 2 μm. Furthermore, compared with thermal stress curve in Si around the conventional copper TSV, thermal stress curve in Si around the low TEC copper TSV was much lower and the KOZ also was reduced to about 1 μm.

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