Practical Electron Microscopy and Database

An Online Book, Second Edition by Dr. Yougui Liao (2006)

Practical Electron Microscopy and Database - An Online Book

Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix

Passive Voltage Contrast (PVC) of pn-Junction Structures/Diodes

In integrated circuits (ICs), there are many contacts formed by combining doped materials, semiconducting materials, metals, and/or alloys. For instance, in Figure 3856 the contacts formed between the two doped regions results in pn junctions (diodes). The metal plug is positively charged in Figure 3856 (a) because the pn junction is reverse-biased due to the emission of secondary electrons (SEs), while it is not charged in Figure 3856 (b) because the pn junction is forward-biased. Therefore, the metal plug appears dark in Figure 3856 (a) while it appears bright in Figure 3856 (b).

Passive voltage contrast (PVC) of pn-junction structure

Figure 3856. Passive voltage contrast (PVC) of pn-junction structures.  

On example is that for SiC (Silicon Carbide) materials, while the sharpest transition is observed between 2.5 and 3.0 kV, a voltage such as 2.0 kV offers the best contrast for specific n+/p- well transitions. (page657.)