Abstract
Intrinsic mechanical stresses in device structures with strained SiGe and Ni silicide have been studied. Stresses in blanket films were derived from wafer curvatures after different stages of device processing. The measurement suggested that the temperature coefficient of NiSi linear expansion equals 1.16⋅10-5 K-1. Experiments showed that silicide films on epitaxial layers of SiGe compensated SiGe stresses in a much greater degree compared to what would follow from the thermal contraction model. Electron microscopy revealed that NiSi(Ge) films formed on SiGe had rough surfaces reducing overall stresses in Si/SiGe/NiSi structures. Computer simulations of MOSFETs with embedded SiGe Source/Drain regions indicated that partial consumption of SiGe layers at silicidation, tensile stress developed in NiSi films due to the thermal contraction and silicide-SiGe interface roughness might reduce compressive stresses in MOSFET channels by 15 - 40%.
Published Version
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