Thickness-Dependent Crystallization and Device Performance in Ta-Doped Ge ₂ Sb ₂ Te ₅ Phase Change Memory

Reducing the size of phase change memory cells improves integration density while simultaneously lowering programming energy consumption. Among various scaling strategies, thinning the phase-change layer represents a particularly direct and practical approach. This study presents a comprehensive investigation of the thickness-dependent properties of Ta-doped Ge2Sb2Te5 (Ta-GST) films and their influence on device performance. Unlike undoped GST, Ta-GST exhibits distinct crystallization behavior; thinner films display reduced crystallization temperatures, which we attribute to a lower activation energy and a higher susceptibility to nucleation in the amorphous phase. Although data retention decreases with reduced thickness, even the 3 nm Ta-GST film maintains a 10-year retention capability at 87 °C, satisfying commercial application requirements. Moreover, grain refinement in thinner films leads to a lower operating power. The device incorporating a 10 nm Ta-GST layer demonstrates optimal overall performance, achieving a switching speed of 6 ns, an energy consumption of 0.828 nJ, and an endurance exceeding 6 × 106 cycles. This work elucidates the fundamental relationship between film thickness and device characteristics in Ta-GST-based memory, offering valuable insights into the development of high-density phase-change memory technologies.