Efficient contact screening of compact NVMs for high reliabilty automotive applications

In modern automotive designs double contacts are mandatory to achieve high reliability products and avoid field returns due to contact issues during the lifetime of the product. Using double contacts in compact digital IPs like RAM, ROM or NVMs leads to a dramatic area penalty. High area efficient NMVs are using shared contacts to minimize the area needed to realize the NVM bit cells. Using double contacts would lead to an area increase of approx. 50% of the NVM memory plane. The high quality standard defined for automotive applications can only be fulfilled with a sophisticated contact screening procedure. This work will present a contact screening procedure which is able to detect contacts with a resistivity outside the main contact resistivity distribution. Those outlier have a potential danger to fail during lifetime as shown in this paper.