Invalidating mechanism of bis (3-sulfopropyl) disulfide (SPS) during copper via-filling process

The invalidating process and related mechanism of bis (3-sulfopropyl) disulfide (SPS) during copper via-filling process were investigated by means of electrochemical polarization measurement, and the mass spectrometry (MS) testing was employed to confirm the molecular weight (MW) and the structure of SPS invalidating products. Meanwhile, quantum chemistry calculation was used to verify the rationality of the proposed invalidating course. These results suggest that the solution containing SPS has invalidated after the passed charges (PC) reached 15 Ah L−1 under electrifying condition. The adsorption ability of SPS decrease gradually with the increase of PC during the invalidating process. The invalidation of SPS is an oxidation process related to the dissolved oxygen in the solution, during which the active functional group -S-S- is oxidized to -SOx-SOy-. As a result, the accelerating effect of SPS on copper reduction will gradually diminish.