Author:

Keywords:

Science & Technology, Technology, Physical Sciences, Materials Science, Multidisciplinary, Physics, Applied, Materials Science, Physics, LOW DIELECTRIC-CONSTANT, PASSIVATION LAYER, PLASMA DAMAGE, ULTRALOW-K, FILMS, POROSITY, RECOMBINATION, MODEL, 0204 Condensed Matter Physics, 0306 Physical Chemistry (incl. Structural), 3406 Physical chemistry, 5104 Condensed matter physics

Abstract:

Low temperature plasma etching of porous organosilicate low-k films is studied, in an ICP chamber with cryo-cooled substrate holder, using Fluorine-based plasma discharges. It is demonstrated that plasma-induced damage is significantly reduced when the base temperature is below a threshold T c that depends on pore size of low-k materials. For T Tc, almost no carbon depletion is observed and the k-value degradation is negligible. It is shown that protection occurs mainly through the condensation of the etch by-products and their ability to seal the open pores against radical diffusion. By addition of SiF4 and O2 into the gas discharge, plasma-induced damage is further reduced, as a result of SiO xFy deposition. Vertical trench profiles are obtained in patterned structures, using an inorganic hard mask. The damage reduction mechanism is discussed and a protection model is proposed. © 2013 The Electrochemical Society.