The Precipitation Behaviour of Copper in Silicon Single Crystals

The precipitation behaviour of copper in silicon is examined from a macroscopic point of view by means of I.R. microscopy, X‐ray micrography, and etching. It is shown that the arms of the starts and the “needles” commonly observed in silicon which is heavily decorated with copper, have the form of “swords” parallel to the (111) and pointing in the 〈110〉 directions. These sword‐like regions are built up of a large number of small copper containing specks and dislocations. A mechanism is proposed which explains the nucleation and growth of the decoration‐patterns. This is based on indentation by oxygen containing precipitates and climb of the resulting fresh dislocation. The X‐ray experiments show that, although decorated dislocations produce a broadened image and complete extinction cannot be obtained, the determination of the Burgers vector is still possible.