Prevention of Physical Property Changes While Being Kept at Room Temperature on the Electrodeposited Copper

In the electrodeposition of copper, some sort of additives such as brighteners like Bis-(3-sulfopropyl)-disulfide (SPS) are added to the bath to produce a smooth surface. But the deposited copper using this type of bath shows the physical property changes while being kept at room temperature. In this research, an additive that can prevent property changes was searched for and the explanation of why the additive has that effect was investigated.Adding Sodium 2-mercapto-1H-benzoimidazole-5-sulfonate dihydrate (2M-5S) enabled the prevention of physical property changes while keeping the surface smooth. Since the correlation of grain size and tensile strength of the deposited copper using the 2M-5S added bath followed the Hall-Petch equation, the property was thought to be dominated by grain size, and the prevention of property changes was thought to be caused by the prevention of re-crystallization due to the pinning effect of the impurities in the copper.2M-5S was conjectured to react with Diaryl-dimethyl-ammonium-chloride Polymer (DDAC) and adsorb to the cathode together, which was also conjectured to be a possible cause of the increase of impurities incorporated into the copper.