Probing strain at the nanoscale with X-ray diffraction in microelectronic materials induced by stressor elements

摘要

The scaling of device dimensions in complementary metal-oxide semiconductor technology has necessitated improvements in transistor mobility achieved through strain engineering. The efficacy of different strain engineering methodologies must be experimentally determined within the actual transistor layout both at a submicron scale and non-destructively. A comparison of several techniques shows that microbeam and nanobeam X-ray diffraction allows us to quantify deformation generated within the Si-based channel regions and crystalline embedded stressor elements. Strain and rotation distributions within silicon-on-insulator (SOI) device layers induced by overlying, compressively stressed, Si_3N_4 features were mapped as a function of stressor linewidth, illustrating the extent of interaction due to its free edges. Strain within SOI device channels and that within adjacent, embedded source/drain e-Si(C) structures was also determined. A comparison of these measurements to the corresponding strain distributions predicted by different mechanical models confirmed the elastic response within the microelectronic features, where the Eshelby inclusion and boundary element methods provide a better match to experimental data than the approach based on edge-forces.