a thermally insulated memory device includes a memory cell , the memory cell having electrodes with a via extending therebetween , a thermal insulator within the via and defining a void extending between the electrode surfaces . a memory material , such as a phase change material , is within the void and electrically couples the electrodes to create a memory material element . the thermal insulator helps to reduce the power required to operate the memory material element . an electrode may contact the outer surface of a plug to accommodate any imperfections , such as the void - type imperfections , at the plug surface . methods for making the device and accommodating plug surface imperfections are also disclosed .