4 - Surface Analytical Techniques Applied to Cleaning Processes

Abstract

In different cleaning and decontamination applications, a wide range of surface analysis techniques can be used, and six commonly used methods; X-ray photoelectron spectroscopy (XPS) or electron spectroscopy for chemical analysis (ESCA), time-of-flight secondary ion mass spectrometry (ToF-SIMS), Auger electron spectroscopy (AES), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray analysis (EDX) (SEM or ESEM), and contact angle; are discussed in detail in this chapter. In many cases, there is a high potential in using several surface analysis techniques and combining the results to get as much information as possible about the cleaning/decontamination of different surfaces. For example, differences in analysis depth between methods can be used to detect enrichment of contamination in the outermost surface layer, or to detect different thicknesses of contamination layers. For thin monolayers of contamination, surface sensitive methods with nanometer analysis depths such as XPS, ToF-SIMS, AES, or contact angle is the choice, as compared to thicker contamination layers where micrometer-level-sensitive techniques such as FT-IR and EDX can be used. The contact angle is often the most direct indication that a surface is contaminated and is sometimes overlooked as a very surface-sensitive analysis tool. XPS and ToF-SIMS provide complementary information, since both are very surface-sensitive techniques with analysis depth in the nanometer range.