A memory cell structure and method to form such structure. An example memory cell includes a bottom electrode formed within a substrate. The memory cell also includes a phase change memory element in contact with the bottom electrode. The memory cell includes a liner laterally surrounding the phase change memory element. The liner includes dielectric material that is thermally conductive and electrically insulating. The memory cell includes an insulating dielectric layer laterally surrounding the liner. The insulating dielectric layer includes material having a lower thermal conductivity than that of the liner.