Towards the integration of both ROM and RAM functions phase change memory cells on a single die for system-on-chip (SOC) applications

We discovered that by changing the dielectric capping layer above the phase change memory element we can change the SET speed and data retention of the memory. This allows us, for the first time, to integrate memories of different functions on the same chip with simple processes. By using a low temperature silicon nitride capping material we can get fast SET speed down to 20ns. With a high temperature silicon nitride capping material, on the other hand, data retention is increased to > 400 years at 85°C. Based on these discoveries, we propose a unified embedded memory solution which provides both ROM and RAM functions in a single chip for SOC applications.