Cu TSV Filling with Cetyltrimethyl Ammonium Cations (CTA+) and Br-
Authors: Eom Hui Won , Kwak Hae Jin , Kim Myung Jun 
Published: February 2024

Through silicon via (TSV) technology is essential for the three-dimensional packaging of electronic devices. After creating high-aspect-ratio vias, Cu electrodeposition is performed to achieve defect-free Cu interconnection. The most important purpose of electrodeposition process is to fill the features without any defects, and this process is called superfilling, superconformal deposition, or bottom-up filling. Since TSV is a key component for the packaging of semiconductor devices, various research on the electrodeposition process for TSV filling have been studied. Defect-free TSV filling can be achieved by introducing appropriate organic/inorganic additives into the electrolyte and the filling performance can be promoted by pulse reverse electrodeposition.1-3 Generally, it has been reported that Cu bottom-up filling at TSVs can be obtained by three-additive combinations (suppressor, accelerator, and leveler) or by using a single suppressor. Tetronic 701 is the most representative suppressor in a single-additive filling method, which was based on S-shaped negative differential resistance (S-NDR) behavior.4-6 In the case of three-additive systems, various levelers that contained ammonium functional groups, a polymeric suppressor, and an accelerator have been researched.7,8 Furthermore, it has been reported that halide ions (Br- and I-) can act as levelers for inducing Cu bottom-up filling at TSVs.9,10 This study investigated the effects of cetyltrimethyl ammonium cation (CTA+) and halide ion on TSV filling in the presence of an accelerator and polymeric suppressor. The influences of two halide ions, Cl- and Br-, on the adsorption of CTA+ and their convection dependency were studied. This presentation will introduce the electrochemical behaviors of halide ions and CTA+ and defect-free filling using the optimum combination of these additives.

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Figure 1