Surface-Tensile-Stress Induced Polishing-Voids Suppression via H2O2 Oxidizer Effect in Cross-Point Phase-Change-Memory-Cells

Abstract

The chemical-mechanical-planarization (CMP) of the Ge-doped SbTe (Ge-ST) film deposited by atomic layer deposition (ALD) is essentially necessary for 3-dimensional (3D) cross-point phase-change-memory (PCM) array, producing indispensably the surface-tensile-stress inducing polishing-voids due to the corrosion of the Ge-ST film and structural tensile stress in the confined memory-cells with ∼20-nm-diameter. The oxidizer (i.e., H2O2) in a CMP slurry played an important role to suppress the generation of the polishing voids via strong chemical oxidation of Sb2O5 and TeO2 of the Ge-ST film surface to avoid a corrosion process during CMP. The suppression efficiency of the polishing voids greatly depended on the H2O2 concentration in a ALD Ge-ST-film CMP of the confined memory-cell array; i.e., the polishing voids could disappear completely greater than a specific H2O2 concentration (i.e., 4wt%).