Open contact analysis of single bit failure in 0.18 μm technology

Single bit failure is the most common failure mode in static random access memory. Although a failing cell can be easily localized with bitmap data, the exact defect location within the failing cell cannot be found immediately, especially when a defect is related to contact. In this paper, a technique of contact-level passive voltage contrast has been proposed to detect such defects for a single bit failure. After an open contact was identified, subsequent transmission electron microscope analysis was performed and it was found that the root cause for the open contact was poly residue.