Cross-Sectioning:

Cross section analysis or micro sectioning analysis is a destructive failure analysis technique to expose a plane of interest in a specimen such as a die cross-section, connector cross-section, solder ball cross-section, plated materials cross-section, capacitor cross-section, resistor cross-section, metal cross-section, PCB Cross Section analysis, or any other device for further analysis or inspection. 

Sample preparation consists of cleaning, mounting, and encapsulation of the specimen in polyester or epoxy resin. These steps provide support, stability, and protection.  Sometimes, a sample is sawed to reduce its size prior to encapsulation. This is usually done to fit the specimen perfectly into the mold, as well as to reduce the grinding needed during actual sectioning.

Cross-section and SEM analysis of a semiconductor die can identify the internal structure of the sample during a failure analysis or reverse engineering.