Methods, systems, and devices related to a memory device with a thermal barrier are described. The thermal barrier (e.g., a low density thermal barrier) may be positioned between an access line (e.g., a digit line or a word line) and a cell component. The thermal barrier may be formed on the surface of a barrier material by applying a plasma treatment to the barrier material. The thermal barrier may have a lower density than the barrier material and may be configured to thermally insulate the cell component from thermal energy generated in the memory device, among other benefits.