Kim Youjung, Jin Sanghyun, Park Kimoon, Lee Jinhyun, Lim Jae-Hong, Yoo Bongyoung
Department of Materials Science and Chemical Engineering, Hanyang University, Ansan, South Korea.
Department of Material Engineering, Hanyang University, Ansan, South Korea.
Front Chem. 2020 Oct 14;8:771. doi: 10.3389/fchem.2020.00771. eCollection 2020.
Thermal stress induced by annealing the Cu filling of through-silicon vias (TSVs) requires further investigation as it can inhibit the performance of semiconductor devices. This study reports the filling behavior of TSVs prepared using direct current and pulse current Cu electrodeposition with and without pre-annealing. The thermal extrusion of Cu inside the TSVs was studied by observing the extrusion behavior after annealing and the changes in grain orientation using scanning electron microscopy and electron backscatter diffraction. The bottom-up filling ratio achieved by the direct current approach decreased because the current was used both to fill the TSV and to grow bump defects on the top surface of the wafer. In contrast, pulse current electrodeposition yielded an improved TSV bottom-up filling ratio and no bump defects, which is attributable to strong suppression and thin diffusion layer. Moreover, Cu deposited with a pulse current exhibited lesser thermal extrusion, which was attributed to the formation of nanotwins and a change in the grain orientation from random to (101). Based on the results, thermal extrusion of the total area of the TSVs could be obtained by pulse current electrodeposition with pre-annealing.
对硅通孔（TSV）铜填充进行退火所引起的热应力需要进一步研究，因为它会抑制半导体器件的性能。本研究报告了使用直流和脉冲电流进行铜电镀且有无预退火情况下制备的TSV的填充行为。通过使用扫描电子显微镜和电子背散射衍射观察退火后的挤压行为和晶粒取向变化，研究了TSV内部铜的热挤压情况。直流方法实现的自下而上填充率降低，因为电流既用于填充TSV，又用于在晶圆顶表面生长凸块缺陷。相比之下，脉冲电流电镀提高了TSV的自下而上填充率且无凸块缺陷，这归因于强抑制作用和薄扩散层。此外，脉冲电流沉积的铜表现出较小的热挤压，这归因于纳米孪晶的形成以及晶粒取向从随机变为（101）。基于这些结果，通过预退火的脉冲电流电镀可以实现TSV总面积的热挤压。
