Test structure and methodology for experimental extraction of threshold voltage shifts due to quantum mechanical effects in MOS inversion layers

This paper reports the test structure and methodology that has been developed to experimentally extract the threshold voltage shifts ⟨ΔV_T⟩ due to quantum mechanical (QM) effects in both electron and hole MOS inversion layers. Compared to classical calculations, which ignore QM effects, these effects are found to cause a significant increase in the threshold voltage on the order of 100 mV in MOSFET devices fabricated with oxide thicknesses and doping levels anticipated for technologies with gate lengths ⩽0.25 μm. ΔV _T has been extracted from experimental devices with doping levels ranging from 5×10¹⁵ cm^-3 to 1×10¹⁸ cm^-3, and recently developed theoretical models are found to agree well with the results. Emphasis has been placed on developing a suitable test structure and methodology which enables the extraction of QM effects with little known error