A Comprehensive Review of DRAM NBTI Issues and Solutions

A comprehensive review of NBTI issues and their preventions were summarized over the past years. The NBTI related process issues, degradation mechanism, and process solution were systemically summarized. We also analyzed some NBTI risk circuits and provided improve suggestions to enlarge DRAM circuit NBTI tolerance. To disclosure the circuit level real risk, a new methodology was investigated with quiz-static DC stress on ring oscillator. Its degradation exhibits a good corelation to that of single device level NBTI performance, and can be used to guide the definition of NBTI specification. This work provides some valuable insights to DRAM NBTI solutions.