Copper Precipitation on Dislocations in Silicon

Abstract

Precipitates formed by copper diffused into silicon crystals were studied by optical means using an infrared image tube. Linear aggregates are identified as dislocations by correlation with etch pits. Dislocations in as‐grown crystals are usually curvilinear. Dislocation loops formed during plastic deformation consist of straight‐line composite portions and pure screw portions, all of which lie in 〈110〉 directions. Precipitates frequently are not found on screw dislocations; when present they differ in detail from those on composites. Interactions between adjacent dislocations can be seen. Etch pits associated with either composite or screw dislocations are similar in form, indicating that the pits formed in as‐grown crystals by the technique described identify all the dislocations. Dislocation loops enter from the surface upon deformation of crystals with relatively few grown‐in dislocations. Dislocation loops formed entirely within the crystal in patterns consistent with operation of the Frank‐Read mechanism are observed in less perfect crystals.