Investigation of low temperature SRAM and ROM failures to enable the replacement of cold test insertion by room temperature test

The replacement of cold test insertion by room temperature test is one possibility of cost reduction. Therefore, a screening concept at room temperature was implemented to address the low temperature failures too. Although, a clever screening concept was able to find most of the low temperature failures, some still could not be caught. To enable the cold test replacement the failure mechanisms of these failures had to be understood. This paper describes the analysis of SRAM and ROM cells failing at low temperature, which could not be detected by this screening concept. It includes the electrical characterisation as well as the physical root cause finding.