Porous SiOCH post plasma damage characterization using ellipsometric porosimetry

Abstract

Porous ultra low-κ (ULK) dielectrics are used to reduce resistance-capacitance delay for advanced CMOS interconnects. Since the porosity leads to an increased sensitivity of the material to cleaning, etching and ashing plasmas, new characterization techniques are needed to assess the ULK properties during its integration. We show that ellipsometric porosimetry (EP), especially with the combination of several solvents, can be successfully used to characterize porous SiOCH films after different plasma treatments, using reducing and oxidizing chemistries (NH3, H2, CH 4 or O2). The characterization of the plasma modified layer is presented and discussed in terms of thickness, hydrophobicity (EP and water contact angle) and κ value. In addition, infrared spectroscopy is used to quantify the methyl (Si-CH3) depletion. Finally the plasma sealing efficiency is quantified by studying the solvent penetration kinetics. © 2009 American Institute of Physics.