Techniques for Lapping and Staining Ion‐Implanted Layers

A technique to determine junction depths in silicon to an accuracy of ±200Å by angle lapping and staining is described, together with extensive tests on the accuracy of staining with copper sulfate solution. It is shown that in the presence of high illumination, the stained junctions are accurately and reproducibly delineated to ±200Å. A possible staining mechanism involving electrodeposition of copper ions under intense illumination is proposed to explain that staining can be accurate to ∼200Å of the metallurgical junction.