EFFECT OF STRESS AND COMPOSITION ON THE RAMAN-SPECTRA OF ETCH-STOP SIGEB LAYERS

Si-1-(x+y)GexBy strained layers on Si (x less than or equal to 3.4% y less than or equal to 0.4%) have been analyzed by Raman spectroscopy. Stress in the layers has not been observed to affect the Fano interact ion parameters of the first-order Si-Si Raman line. These parameters h ave been determined in the range of B concentrations from 5x10(19) to 2x10(20) cm(-3) and Ge fractions from 1% to 3.4%. The observed shift i n the spectra has been found to depend linearly on both the germanium and baron contents, These data have been correlated with the stress me asured in the layers by mechanical wafer bow measurements. The depende nce of the Raman shift on the germanium content and strain agrees with that previously reported for strained SiGe layers. According to these data, Raman spectroscopy appears as an interesting tool for the nonde structive assessment of stress and composition of these layers. (C) 19 96 American Institute of Physics.