Film & Composition Metrology

Film Thickness and Composition

Key techniques for characterizing deposited films:

• Spectroscopic Ellipsometry (SE): Measures how polarized light changes upon reflection from a film stack. Extracts thickness and optical constants for multiple layers simultaneously. The primary production tool for film thickness (1–10,000 nm range).
• X-Ray Fluorescence (XRF): X-rays excite atoms in the film, which emit characteristic fluorescence. Provides composition and thickness for metal films. Non-destructive and fast.
• X-Ray Photoelectron Spectroscopy (XPS): Measures the binding energies of photoelectrons to determine chemical composition and bonding states of surface layers. Critical for understanding gate stack chemistry.
• SIMS (Secondary Ion Mass Spectrometry): Sputters the surface with an ion beam and analyzes ejected atoms with a mass spectrometer. Gives depth profiles of composition with ppb sensitivity. Destructive but uniquely powerful for dopant profiling.