A Deeper Look at Bottom-up Copper Deposition in High Aspect Ratio through Silicon Vias

Tuesday, 15 May 2018: 17:40
Room 211 (Washington State Convention Center)
D. Josell, M. Silva, J. Kildon, and T. P. Moffat (NIST)
Superconformal copper electrodeposition in larger features, as in smaller features, is influenced by both suppressor and chloride in the copper electrolyte. Different behaviors are observed in electroanalytical measurements of low and high chloride electrolytes. One significant difference is the dependence of suppression breakdown and associated S-shaped negative differential resistance (S-NDR) on transport assessed using a rotating disk electrode. Superconformal filling of 56 μm tall, annular Through Silicon Vias (TSVs) from the electrolytes can exhibit the bottom-up evolution previously noted for the Cu system as well as transient or steady-state passivation breakdown along the TSV sidewall, with uniform deposition below, previously demonstrated with Au, Ni and Co S-NDR systems. As both filling geometries are predicted by S-NDR based models, I will discuss the factors that we believe determine the experimental filling geometry.