BEOL Process Effects on ePCM Reliability

The effect of back-end of line (BEOL) process on cell performance and reliability of Phase-Change Memory embedded in a 28nm FD-SOI platform (ePCM) is discussed. The microscopic evolution of the Ge-rich GST alloy during process is the focus of the first part of the paper. A new metric for quantification of active material modifications is introduced to better follow its evolution with process sequence. Ge clustering has been shown to occur during the fabrication, impacting the pristine resistance and the after forming cell performance. Two different BEOL processes are then benchmarked in terms of key performance. An optimized process is identified, and an extensive electrical characterization of array performance and reliability is done on the full 16MB chip. The optimized BEOL process results in a memory cell fully compatible with the requirements for demanding automotive applications.

Automated summary

The effect of back-end of line (BEOL) process on the performance and reliability of Phase-Change Memory embedded in a 28nm FD-SOI platform (ePCM) is discussed in this paper. The study focuses on the microscopic evolution of the Ge-rich GST alloy during the process. It is found that Ge clustering occurs during fabrication, affecting the resistance and cell performance. An optimized process is identified to meet the requirements for demanding automotive applications.