The Korean Society of Surface Science and Engineering

This study focuses on the evaluation of ultra-thin copper foil properties used in the bottom-up copper electroplating process for filling Through Glass Via(TGV) holes. The foils are also applicable for forming high-density Redistribution Layers (RDL) on glass substrates with pre-formed TGVs. To ensure analytical accuracy, multiple complementary characterization methods were employed for surface and interface analysis and for assessing the release layer properties. The investigation covered various physical properties, including surface and cross-sectional morphology, layer structure, thickness, and crystallite size. In particular, detailed analyses were conducted on key layers affecting adhesion strength such as the Cu nodule layer, interfacial layer, adhesion layer, and release layer. Four types of copper foils were characterized using similar procedures. Based on thorough analyses, foil #1 was identified as having a Carrier Cu/Ni/Organic layer/Thin Cu structure; foil #2 exhibited a multilayer structure comprising Carrier Cu/Ni-P/Mo-Fe-Ni/Ni/Thin Cu. foil #3 showed a Carrier Cu/Ni-P (diffusion barrier)/Mo-Fe-Ni (release layer)/Thin Cu/Nodulous Cu structure; and foil #4 was confirmed to have a Carrier Cu/Ni-Mo/Thin Cu/nodule Cu structure. This study is expected to provide fundamental insights into release characteristics through detailed analyses of the carrier copper foil structure, establish cross-analytical methodologies, and suggest design strategies for optimal release performance, thereby supporting the application of ultra-thin foils in TGV technology.

키워드 TGV(Through Glass Via); Buttom-up copper electroplating; Release copper foil; Surface analysis; interface characteristic.