In-line Si1-xGex epitaxial process monitoring and diagnostics using multiwavelength high resolution micro-Raman spectroscopy

Multiwavelength, high resolution micro-Raman spectroscopy was applied to in-line process monitoring and diagnostics of undoped and B-doped Si1-xGex epitaxy on Si(100) device wafers. This noncontact technique was used to monitor the Ge content, B concentration and thickness of single and double Si1-xGex epitaxial layers. Epitaxial process problems were diagnosed nondestructively. Raman peak positions and full-width-at-half-maximum of the Si-Si peak(s) from the Si1-xGex epitaxial layer(s) and Si substrates, in the wavenumber range of 475 ∼ 535 cm-1, were monitored under ultraviolet and visible excitation wavelengths. The Ge content, B concentration and Si1-xGex epitaxial film structures were verified by secondary ion mass spectroscopy (SIMS) depth profiling results. In-line monitoring of Si-Si and Si Raman peaks is very effective in noncontact material property characterization, epitaxial process optimization, and quality control applications.