H. T. Chen, Y. B. Zou, B. Da, Z. J. Ding
This research establishes a clear definition and simulation framework for SE1/SE2 secondary electrons , revealing the physical mechanisms underlying image formation in Scanning Electron Microscopy (SEM) at a resolution of approximately 0.8 nm. It demonstrates that the topography-modulated SE2 signal makes a decisive contribution to ultra-high resolution. Through quantitative simulation of secondary electron behavior under incident electron energies ranging from 0.1 to 30 keV, this work corrects the traditional misconception that "SE2 is merely a background signal" and redefines the physical upper limit of electron beam imaging resolution. This mechanistic clarification helps drive the optimization of CD-SEM , Review-SEM, and defect inspection equipment in the semiconductor industry toward sub-nanometer resolution, providing crucial support for critical dimension metrology and minute defect recognition at the 2 nm process node and beyond.