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.
Precipitates and prismatic punching
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

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go to 6.1.1 Observation of Dislocations and Other Defects

go to Precipitates and Dislocations

© H. Föll (Defects - Script)