SRAM Nano-characterization
Mattia SILVESTRE
(LFoundry)
Abstract
SRAMs are not only a very common type of embedded memories in ICs but they also play a major role as a vehicle for new process generation technology for process-defect analysis and electrical performances.
Very frequent failure modes are single bit failures (one failing bit on memories with array size of Mega-bits) and they determine a big challenge for Failure Analysis since the cause of the electrical failure of one single bit cell could be related to structural abnormalities localized in a region of few nanometers.
The tradeoff between the resolution of the TEM, that is the main analytical tool used for the physical analysis on nanoscaled structures, and its field of view necessarily requires an enhancement of the fault location: In fact the resolution of the electrical analysis is limited, in this case, to one bit cell and only by means of nanoprobing analysis one can isolate the single failing transistor among the entire cell set. This presentation will show how nanoprobing helps the Physical Failure Analysis on structural anomalies causing SRAM single bits failure improving both physical fault location and electrical analysis resolution.
