Contact resistance of TiW to Phase Change Material in the amorphous and crystalline states

Electrical characterisation of metal to Phase Change Material (PCM) contacts is necessary for optimum power transfer during switching of a Phase Change Random Access Memory (PCRAM) cell. In this article, titanium tungsten (Ti
_0.3
W
_0.7
) to two phase change materials; doped-Sb
₂
Te and Ge
₂
Sb
₂
Te
₅
are characterised using Circular Transfer Length Method (CTLM) structures. A metal lift off process with a maximum process temperature of 120°C allows processing of these CTLM structures below the crystallization temperature of PCM used. The specific contact resistance for TiW-PCM contacts with PCM in amorphous (high resistive) and crystalline (low resistive) phases is extracted from these CTLM measurements.