Inspection of the Current-Mirror Mismatch by Secondary Electron Potential Contrast With In Situ Nanoprobe Biasing

The mismatch mechanism in a current mirror consisting of laterally diffused p-channel MOS (LDPMOS) technology was investigated using a scanning electron microscope (SEM) with in situ nanoprobing. The electrical measurement found a saturation current mismatch of 52 μA between the LDPMOS transistors. Furthermore, the proposed inspection identified successfully 0.4-μm p-well layer misalignment, which was the root cause of the mismatch. This letter demonstrates that an in situ nanoprobing system is a powerful tool for enhancing p-well dopant contrast in a SEM, analyzing site-specific failures, and studying device physics under a dynamic scope.