TXRF – Total X-Ray Fluorescence

Total X-Ray Fluorescence (TXRF) is a sensitive method for analysis of trace metals on a silicon wafer surface. TXRF uses an incident x-ray beam to excite metal contamination on the wafer surface giving off fluorescence.  The fluorescence signal that is collected and analyzed.  The angle of the incident x-ray beam is very shallow such that only the near surface (about 400 A) of the wafer is being analyzed.  Transition metals such as Cr, Fe, Ni and others can be analyzed with a detection limit of 1E9 atoms/cm2. Typically a W anode can provide satisfactory results for most applications – however an alternate anode such as Ag or Mo can also be used to access higher Z elements such as Br and As. TXRF is particularly useful for volatile elements as Ar, S, Cl and Br. These elements cannot be measured with other trace methods that require solution chemistry. On the other hand TXRF is not suitable for light elements such as Li, B, N, F, and Na. Sensitivity for Mg and Al is also poor.

Instruments: