Spectroscopic and Topographic Investigations of Nanoparticle Abrasive retention in Polyurethane CMP Pads for Cu CMP

Abstract

ABSTRACTA spectroscopic and topographic investigation of abrasive nanoparticle retention in polyurethane chemical mechanical planarization (CMP) pads has been carried out as a function of ex situ pad conditioning parameters for Cu CMP. X-ray photoelectron spectroscopy (XPS) and scanning electron microscope energy dispersive spectroscopy (SEM-EDS) were utilized to quantitatively characterize the presence of alumina nanoabrasive in the pad following Cu CMP. As expected, conditioning did not modify the overall pad morphology but did increase local asperity roughness with increasing conditioner downforce. As expected, the magnitude of the conditioner downforce reduced the overall average alumina nanoabrasive retention, albeit weakly, as determined via XPS. However, local EDS analysis revealed that increased downforce does significantly reduce nanoabrasive retention at pad asperities. In contrast, increased downforce increased the amount of nanoabrasive present in the polyurethane pad surface pores. Moreover, overall conditioning time was shown to be a more dominant parameter compared to conditioner downforce regarding removal of abrasive particles from both pad asperities and pores.