Laser etching is one of the predominant methods used for the identification marking of integrated circuits. This is partly due to the fact that laser marking is a tamper proof method of identification. Tamper proof marking has helped greatly reduce IC fraud, the selling of IC is for higher speeds and specifications than they were produced for.
Metrology
Step Height
As IC packages have become smaller and thinner the requirement for measuring step height of laser etching has become more important. The target depth of the laser etch is defined by two requirements. Firstly, it must be deep enough to provide tamper proof marking that can be read by IC identification systems and secondly, it must be shallow enough not to damage the circuits on the chip.
Roughness
The surface finish of the etched mark is an important factor in the easy reading of the final identification, whether by machine or human eye. The rougher the surface, the more light that is scattered and this increases the contrast of the mark to its surrounding surfaces.