In this paper, we present a thorough physical-chemical analysis of an engineered PCM stack, where the integration of C-doping and the use of a Ti top layer allow obtaining an Amorphous As-Deposited (A-AD) phase stable against Back End-Of-Line (BEOL) thermal budget. This PCM stack is then integrated in devices, which are extensively tested in order to validate a novel pre-coding technique compliant to the Pb-free soldering reflow issue. Finally, an original design to optimize the distribution dispersion is presented.