GeSbTe deposition for the PRAM application

GeSbTe (GST) chalcogenide thin films for the phase-change random access memory (PRAM) were deposited by an atomic layer deposition (ALD) process. New precursors for GST thin films made with an ALD process were synthesized. Among the synthesized precursors, Ge(N(CH3)2)4, Sb(N(CH3)2)4, and Te(i-Pr)2 (i-Pr = iso-propyl) were selected. Using the above precursors, GST thin films were deposited using an H2 plasma-assisted ALD process. Film resistivity abruptly changed after an N2 annealing process above a temperature of 350 8C. Crosssectional scanning electron microscope (SEM) photographs of the GST films on the patterned substrate with aspect ratio of 7 shows that the step coverage is about 90%.