Foreign Material Identification by FTIR Characterization with Novel FIB Lamella Preparation

The impact of Foreign Material (FM) on the semiconductor manufacturing process is well established. For organic corrosive FM that are embedded in final devices after assembly, FTIR is one of the preferred characterization techniques by fingerprint identification or database searching. This technique becomes more challenging for smaller FM feature sizes where strong IR interferences in complicated matrices impedes adequate identification. Advances in mapping ATR-FTIR can push lateral sampling resolution to below 2µm pixel size. However, when the interaction volume exceeds the FM size, the resulting IR spectrum is contaminated with the surrounding material leading to weak identifications. In this paper, we demonstrate a Focused Ion Beam (FIB) lamella to reduce matrix effects and further combine the advantages from transmission mode signals to successfully verify the source of a small corrosive FM.