Chemical analysis of metallic contamination on a wafer after wet cleaning

The chemical analysis of trace metallic contamination on a wafer can be achieved by using total reflection X-ray fluorescence (TRXRF) with HF condensation and with poly silicon encapsulation secondary ion mass spectroscopy (PC-STMS). HF condensation can concentrate almost all atoms, such as Fe, Cr, and Ni, within 10 mm of the center of a wafer, which leads to lower detection limits. Poly silicon encapsulation eliminates the surface problems that tend to occur with normal SIMS, which results in good reproducibility. A combination of both methods is suitable for analyzing lower-level contaminations up to 10⁸ atoms/cm² level for many elements such as transient metals and lightly elemental metals. The application of the analyses to wet cleaning reveals the contamination removal and adhesion effects for various solutions and cleaning procedures, as well as variation between experimental cleaning batches