Embodiments of the present invention provide a method that includes providing wafer including multiple cells, each cell including at least one emitter. The method further includes performing a lithographic operation in a word line direction of the wafer across the cells to form pre-heater element arrangements, performing a lithographic operation in a bit line direction of the wafer across the pre-heater element arrangements to form a pre-heater element adjacent each emitter, and performing a lithographic operation in the word line direction across a portion of the pre-heater elements to form a heater element adjacent each emitter. Other embodiments are also described.