Workfunction fluctuations in polycrystalline TiN observed with KPFM and their impact on MOSFETs variability

Abstract

A more realistic approach to evaluate the impact of polycrystalline metal gates on the MOSFET variability is presented. 2D experimental workfunction maps of a polycrystalline TiN layer were obtained by Kelvin Probe Force Microscopy with a nanometer resolution. These data were the input of a device simulator, which allowed us to evaluate the effect of the workfunction fluctuations on MOSFET performance variability. We have demonstrated that in the modelling of TiN workfunction variability not only the different workfunctions of the grains but also the grain boundaries should be included.

Combined nanoscale KPFM characterization and device simulation for the evaluation of the MOSFET variability related to metal gate workfunction fluctuations

“…Note that although a continuous distribution of maximum WFs is obtained, WFs are mostly concentrated at ~4.3 eV and, with less frequency, around ~4.5 eV, suggesting two predominant WFs and indicating a much higher number of nanocrystals with low WF than with high WF. This result, confirmed by XRD [14], is compatible with the presence of two grain orientations in the TiN layer ([111] and [200]) whose WFs are separated by 200 mV [9] . The data obtained from KPFM images add new information on the properties of the polycrystalline metal layer, not taken into account in previous works.…”

“…X-Ray Diffraction (XRD) was used to determine the structure of the TiN layer. The XRD spectrum shows a polycrystalline structure with two peaks [14], that correspond to the [111] and [200] orientations [9]. being the [111] orientation dominant over the [200] one.…”

KPFM Study of Flexible Ferroelectric Polymer/Water Interface for Understanding the Working Principle of Liquid–Solid Triboelectric Nanogenerator

“…[ 24 ] The surface potential is directly related to the difference in work function between the sample and conducting tip which is used in the KPFM measurement. [ 25,26 ] However, this technique can also be used to study the change in charge distribution on the surface of the sample. [ 27 ] Thus, we can use KPFM technique to measure the surface charges being generated on the sample before and after the water drops fall on the surface, which will give a clear idea about the quantity and the type of charges being generated on the surface after water drops come into contact and then roll off and thereby we can verify the contrasting views on the charge generation on the surface of the films after water comes into contact, and it would be possible to propose the electricity generation mechanism in LSTENG.…”

Effectively modulating thermal activated charge transport in organic semiconductors by precise potential barrier engineering

“…To further certify the relationship between potential barrier of GB and grain size, the potential of GB should be directly observed. Kelvin probe force microscopy (KPFM) has been proved as a powerful tool for investigating interface electrical structure of organic devices, which can record surface and interface potential distribution of polycrystalline film [72][73][74] . The potential ∅ B of DNTT films with different grain sizes can be obtained directly through KPFM.…”