Electro-thermal analysis of device geometry dependence on the amorphous cap size in phase change memory devices

Abstract We present the footprint of amorphous cap thickness to facilitate intermediate resistance inside the Phase change memory (PCM) devices with varying geometric parameters, employing electro-thermal analysis. A 2D finite element simulation with axis symmetry is employed to analyze the electro-thermal effect on the PCM device using Ge2Sb2Te5 (GST) as a phase change material. The thermoelectric effects inside the GST are calculated using the material with temperature-dependent features. The overall device performance can be optimized through precise tuning of geometrical parameters. A substantial increase in local temperature profile for the three devices was achieved by varying the amplitude of RESET pulses from 1.6 V to 2.4 V. When the heater increases and the LGST decreases, a reduced amorphous cap thickness (AT) of 30.8 nm is observed. Conversely, reversing these dimensions results in a substantially larger cap thickness of 64 nm. An intermediate cap thickness of 48 nm is obtained when both Lheater and LGST are the same. A thicker amorphous cap leads to a lower peak temperature. Device 2 (Lheater < LGST) exhibits a peak resistance of 16.45 MΩ, with Device 1 (Lheater ≈ LGST) and Device 3 (Lheater > LGST) showing 23.6% and 52% lower values, respectively. These findings are helpful to achieve the multi-bit operations inside the device, which is suitable to emulate the biological synapse.