A Trade-Off Balance Between CU Corrosion and CU Oxide DEFECT

Chemical mechanical polishing plays a vital role in back-end Cu interconnection technology, while Cu corrosion and Cu oxide are two killer defects which may cause the poor contact of metal lines. Here, we study the root causes of these two defects and propose our solutions. Results of design of experiment show that the formation of Cu corrosion and Cu oxide are inversely related to the concentration of clean chemical. By a series of attempts from optimizing clean recipe, adding chemical buff step for pre-protection, calibrating the drop point of upper rinse water, changing nozzle type, adjusting chemical concentration etc., we successfully reduce the above two defects in chemical trend down manner.