Test quality analysis and improvement for an embedded asynchronous FIFO

Embedded First-In First-Out (FIFO) memories are increasingly used in many IC designs. We have created a new full-custom embedded FIFO module with asynchronous read and write clocks, which is at least a factor two smaller and also faster than SRAM-based and standard-cell-based counterparts. The detection qualities of the FIFO test for both hard and weak resistive shorts and opens have been analyzed by an IFA-like method based on analog simulation. The defect coverage of the initial FIFO test for shorts in the bit-cell matrix has been improved by inclusion of an additional data background and low-voltage testing; for low-resistant shorts, 100% defect coverage is obtained. The defect coverage for opens has been improved by a new test procedure which includes waiting periods.