Contactless monitoring of Ge content and B concentration in ultrathin single and double layer Si1-xGex epitaxial films using multiwavelength micro-Raman spectroscopy

Non-contact monitoring of Ge content and B concentration in single and double Si1-xGex epitaxial layers on Si(100) device wafers was attempted using high-resolution, multiwavelength micro-Raman spectroscopy. The Ge content and B concentration determined by secondary ion mass spectroscopy (SIMS) depth profiling showed very strong correlation with the position and full-width-at-half-maximum of the Si-Si peak from the Si1-xGex epitaxial layers as determined by Raman measurements. High resolution X-ray diffraction (HRXRD) characterization was done for all wafers to determine Ge and B sensitivity and form comparisons with Raman and SIMS analysis. The non-destructive, in-line monitoring of Ge content and B concentration of single and double Si1-xGex epitaxial layers with thickness ranging from 5 ～ 120 nm, on small area monitoring pads, was successfully demonstrated by multiwavelength micro-Raman spectroscopy during epitaxial process optimization, material property verification, and quality control applications.