# Precipitates and Other Defects as Seen with Preferential Etching

| Shown is a preferentially etched part of an integrated circuit. Many kinds of defects are revealed; the interpretation is not necesarily clear.
|  | The big etch pits in the frames of device parts are due to dislocations.
|  | In the structureless area we see pits and hillocks (distinguished because the "black-white vector", the vector from the black part of a small contrast to the white part comes with both signs) and a few very distinctive features consisting of a central pit with "satellites" along one direction.
|  | All these features are most likely due to precipitates. The rows of pits are caused by precipitates that produced a sequence of dislocation loops to relieve the stress in a process known as "prismatic punching".
| What prismatic punching looks like if imaged with a transmission electron microscope at high magnfication can be seen in the link

With frame

6.1.1 Observation of Dislocations and Other Defects

Precipitates and Dislocations

© H. Föll (Defects - Script)