Fault Isolation of DQ Failures in 14 nm SRAM Using Laser Voltage Imaging and Probing

Abstract

Through custom test pattern generation and SRAM design analysis, we present the first demonstration of Laser Voltage Imaging (LVI) and Probing (LVP) for the successful fault isolation and physical analysis of DQ failures within a 14nm SRAM macro. These findings revealed the fail site to reside within the I/O circuitry of the associated failing pin, a previously overlooked location as common block failures are typically associated with physical anomalies within the SRAM periphery.

Descrambling of Embedded SRAM Using a Laser Probe

“…Perform frequency mapping at the toggle frequency and localize memory cells of interest. A process similar to step 3 was reported in FA for the localization of defects in data input/output latches/registers (DQ) [17]. However, the scheme discussed here aims at identifying cells directly in the memory array, not getting signals in the surrounding circuitry and so without any knowledge of the circuit design.…”