Recovery Processes of CMP-Induced Damages for Copper/Porous Silica Damascene Interconnects

Abstract

This paper describes the effects of recovery processes for the degradation caused by chemical mechanical polishing (CMP) in the integration of Cu/porous silica low-kmaterial interconnects(Cu∕po-SiO), in whichSiOCis used as CMP-Cap film (Cap-SiOC) forpo-SiOfilm. The leakage current and capacitance between Cu damascene interconnects increased when Cap-SiOCwas removed by CMP and thepo-SiOwas exposed, because the surfactant in CMP chemicals penetrated thepo-SiOand the hydrophobicity of thepo-SiOdecreased, resulting in the increase of water absorption in thepo-SiO. As a result of the recovery process after CMP, the leakage current has decreased by three orders of magnitude by applying an isopropyl alcohol rinse and 1,3,5,7-tetramethyl-cyclo-tetrasiloxane (TMCTS) gas treatment, and the capacitance has decreased by 15% by applying the TMCTS gas treatment.