Simultaneous Deposition of Different Phase‐Change Alloys Through a Nanopillars Shadow Procedure

Phase Change Memory is a leading emerging nonvolatile memory technology based on the reversible switching between amorphous and crystalline states in Ge‐Sb‐Te alloys. Repeated phase transitions induce elemental redistribution, generating local stoichiometry variations that critically influence device performance. Accessing different compositions within a single specimen is therefore essential for understanding phase change memory (PCM) behavior. We present a deposition methodology enabling the simultaneous formation of phase‐change alloys with nanoscale compositional gradients. The approach uses three Knudsen cells supplying Ge, Sb, and Te, each oriented at 45° relative to the substrate normal. The substrate includes cylindrical nanopillar arrays produced by electron beam lithography, which generate controlled shadowing effects and spatial modulation of the elemental flux. Local composition was characterized using scanning transmission electron microscopy and electron energy loss spectroscopy. The elemental profiles were compared with a ballistic transport model describing trajectories around nanopillars. The experimental and simulated data show agreement. Simulations performed with an alternative configuration, where the three cells are spaced 120°, predict predefined Ge, Sb, and Te‐deficient regions around the pillars. This methodology enables controlled nanoscale stoichiometry engineering and provides a powerful platform for studying composition‐dependent phase‐change mechanisms, supporting the optimization of PCM device performance.