Impact of plasma reactive ion etching on low dielectric constant porous organosilicate films' microstructure and chemical composition

Abstract

The impact of plasma reactive ion etching on hybrid organic/inorganic polymer materials is investigated in detail regarding chemical (composition) and physical (porosity) aspects. Porous low dielectric constant insulating films are used in integrated circuits and these experience plasma etching before the deposition of conductive copper lines. We show that this induces detrimental changes in the film. Notably, chemical composition modifications were characterized by Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) and depth-profiled by Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), whereas fine structural changes were analyzed with 1H, 13C, and 29Si solid-state Nuclear Magnetic Resonance (ssNMR). Evolution of surface properties was measured with Contact Angle (CA) analysis, while porosity variations were probed with Ellipsometric Porosimetry (EP). We show how the complementarity of these techniques enables a thorough description of the impact of the etching process on this low-dielectric constant material, which in turn enables recommendations for the manufacture of microelectronic devices.