In the manufacturing process of semiconductor products, thin film inspection methods vary depending on the purpose. For example, optical such as ellipsometers, sheet resistance film thickness meters, step meters, and cross-sectional scanning electron microscopes (SEM) are used for film thickness management. For analysis of composition, X-ray photoelectron spectroscopy (XPS) or other techniques are used.
Among these techniques, X-ray fluorescence (XRF) spectrometers are used in many processes due to the capability to perform simultaneous film thickness/composition analysis non-destructively, with no contact and no sample preparation. The method is applicable to opaque films (metals or nitride films, etc.) and has excellent reproducibility. Special features of wavelength dispersive XRF (WDX; Wavelength Dispersive XRF) analysis are shown below;
- Analysis of light elements such as B, N and Al
- Sub-nm (Å) level ultra-thin film analysis
- Analysis of layered and compound films
Due to these advantages, the use of WDXRF instruments has been increasing in recent years.