STRUCTURE AND METHOD FOR BIASING PHASE CHANGE MEMORY ARRAY FOR RELIABLE WRITING

摘要

A memory array having memory cells (40, Fig. 5) comprising a diode (42) and a phase change material (23) is reliably programmed by maintaining all unselected memory cells in a reverse biased state. Thus leakage is low and assurance is high that no unselected memory cells are disturbed. In order to avoid disturbing unselected memory cells during sequential writing, previously selected word and bit lines are brought to their unselected voltages before new bit lines and word lines are selected. A modified current mirror structure (70, Fig. 8) controls state switching of the phase change material.