Patent ID: 7906774

Claim:
A phase change memory device, comprising: a substrate; a phase change layer over the substrate; a first electrode electrically connecting a first side of the phase change layer; and a second electrode electrically connecting a second side of the phase change layer, wherein the phase change layer composes mainly of gallium (Ga), antimony (Sb) and tellurium (Te) and unavoidable impurities, having the composition range of Ga x Te y Sb z 5<x<40; 8<y<48; 42<z<80, wherein x+y+z=100, and the phase change layer in the said device is characteristic of: reversible phase change between amorphous and crystalline states upon a pulsed electrical current of appropriate amplitude and duration flowing through the first and second electrodes, wherein the phase change memory device has two reset states and a three-digit per cell memory characteristics.