Optical probing on digital circuit elements (NANDs)

We present a comprehensive study of electro-optical frequency mapping (EOFM) and probing (EOP) on NAND and NAND-like structures with different sizes. Our main objective was to find out, if it is possible to detect single dysfunctional transistors in a NAND structure smaller than the laser spot just by means of the optical signal. We further investigate the impact of parasitic laser voltage signals at different spots/material compositions in the area of the active devices and the dependence of optical signals on different pulse modes of the active devices. We also use phase mode to identify short-time effects within the pulse period and phase shifts between signals at different spots. Additionally, we observe electrical pulse phase shift and focus dependency of laser voltage signals. As we believe that the signal difference between the use of a super luminescence diode (EOFM/EOP) and a laser (LVI/LVP) as light source is relatively small, we will henceforth use the more common terms “LVI” and “LVP”.