At the core of 3D PCM is the use of phase-change materials like chalcogenides, which can exist in either an amorphous (high-resistance) state or a crystalline (low-resistance) state. Data is written to PCM cells by heating these materials using electrical pulses, causing a change in their phase state. Reading data involves measuring the electrical resistance of the material to determine its state. The "3D" aspect comes from stacking multiple layers of PCM cells vertically, dramatically increasing storage density.
