EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Over the past few decades, the field effect transistors (FET) scaling followed mainly Moore’s law. However, with the downscaling of FET reaching its physical limitations, the quest for alternate technological solutions based on new device materials and concepts is on the rise. In this era of “Beyond CMOS”, various new researches and technologies have emerged, which focus on diversifying the device functionality rather than scaling its dimensions. One such concept, which presents the potential of a universal transistor, is called a Reconfigurable Field Effect Transistor (RFET). RFETs can be dynamically programmed to p- or n-polarity by the application of electrostatic potential. In the general case, these are intrinsic silicon nanowire-based transistors typically with two top-gates. One of the gates is used to tune the device polarity while the other gate modulates the flow of charge carriers. Nickel (Ni) is placed at both ends of the nanowire and subsequently, annealing is performed. This results in the formation of NiSi2-Si-NiSi2 Schottky junctions and such devices show ambipolar behavior when controlled by a back-gate or a single top-gate. For unipolar behavior, two top-gates are placed on top of these Schottky junctions. This work aims at the top-down fabrication of Si RFET devices. Flash lamp annealing (FLA) is used for Ni silicidation of the nanowires instead of conventional rapid thermal annealing as the former yields a significantly better control over the silicide progression. Various dielectric materials are explored to gain better capacitive control over the bands for the conduction of the charge carriers. The source-drain contacts and the top-gates are fabricated, followed by electrical characterization of the devices. The fabricated RFET devices demonstrate ION/IOFF ratio of up to 8 orders of magnitude and record pn on-current symmetry of 1.03.