Plasma-surface interactions of nanoporous silica during plasma-based pattern transfer using C/sub 4/F/sub 8/ and C/sub 4/F/sub 8//Ar gas mixtures

Abstract

Summary form only given. Nanoporous materials (NPM) are a compelling class of candidate materials for future microelectronic and optoelectronic applications that require ultra-low dielectric constants and/or refractive indices, respectively. The plasma-surface interactions of NPM are strongly modified relative to conventional homogeneous materials. We have investigated plasma surface interactions of nanoporous silica (NPS) films with porosities of up to 50%, SiO/sub 2/ and organosilicate films in C/sub 4/F/sub 8//Ar discharges, which were well characterized by numerous diagnostics. Surfaces of the various materials after the above plasma processes were studied by X-ray photoemission spectroscopy (XPS) and transmission electron microscopy (TEM) as a function of process conditions. In addition, time-of-flight secondary ion mass spectrometry (SIMS) (in static or dynamic mode) was used to obtain additional information on the compounds formed on the surfaces of these materials, or on variations of elemental densities as a function of depth. The surface modification of NPS upon different plasma processing will be described along with the plasma characterization. The plasma surface interactions are strongly dependent on both plasma properties and surface morphology, and the interaction of these will be discussed in detail.