CHEMICAL-ANALYSIS OF METALLIC CONTAMINATION ON A WAFER AFTER WET CLEANING

The chemical analysis of trace metallic contamination on a wafer can b e achieved by using total reflection X-ray fluorescence (TRXRF) with H F condensation and with poly silicon encapsulation secondary ion mass spectroscopy (PC-SIMS). HF condensation can concentrate almost all ato ms, such as Fe, Cr, and Ni, within 10 mm of the center of a wafer, whi ch leads to lower detection limits. Poly silicon encapsulation elimina tes the surface problems that tend to occur with normal SIMS, which re sults in good reproducibility. A combination of both methods is suitab le for analyzing lower-level contaminations up to 10(8) atoms/cm2 leve l for many elements such as transient metals and lightly elemental met als. The application of the analyses to wet cleaning reveals the conta mination removal and adhesion effects for various solutions and cleani ng procedures, as well as variation between experimental cleaning batc hes.