A Study in Improvement of Anisotropic Copper Wet Etching for Semiconductor Packaging

In this study, the corrosion inhibition behavior of thiourea in highly concentrated copper chloride solutions was investigated through electrochemical analysis and X-ray photoelectron spectroscopy. The results reveal that thiourea inhibits copper corrosion by forming a passive film, which is a copper-thiourea complex generated during the corrosion process. This complex effectively prevents the dissolution of Cu into <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Cu2}^+$</tex>, thereby slowing down the copper corrosion reaction. These findings suggest that the adsorption properties of thiourea during the copper etching process play a crucial role in facilitating the fabrication of semiconductor package substrates with high-density interconnects.