Practical Electron Microscopy and Database

A stroboscopic SEM had been effectively used to evaluate high-speed waveforms in an ECL 4K-bit bipolar RAM. [1] Time resolutions as precise as 500 ps and voltage resolutions of 50 mV had been achieved. Figure 0373a shows the schematic diagram of the stroboscopic SEM system. To measure rapid changes in potential, the pulsed beam must be synchronized with the device under test (DUT), and the relative phase shift between them should be adjustable as needed. Single-delay scanning, where the phase shift is changed once per waveform measurement, is a commonly used method. In this system, multi-delay scanning (MDS) is implemented, where single-delay scanning is repeated, and the signal is stored in line memory until the signal-to-noise ratio reaches a sufficiently high level. MDS was developed to detect potential signals through a passivation layer. The instrument's smallest delay increment is 100 ps, and its maximum delay is 409.5 ns.

[1] H. Todokoro, S. Yoneda, K. Yamaguchi, S. Fukuhara, T. Komoda, Stroboscopic testing of LSIs with low voltage scanning electron microscope, https://doi.org/10.1111/j.1365-2818.1985.tb02685.x, 1985.