Tradeoff between the transistor reconfigurable technology and the zero-temperature-coefficient (ZTC) bias point on BESOI MOSFET

Abstract A tradeoff between transistor reconfigurability and a Zero Temperature Coefficient (ZTC) bias point was observed and analyzed for Back Enhanced SOI (BESOI) MOSFET for the first time. The ZTC is observed only for BESOI MOS with aluminum Source/Drain (S/D) electrodes (ohmic contact with the channel) while the transistor reconfigurability is present only for BESOI MOS with nickel S/D electrodes (Schottky contact). This tradeoff is discussed and demonstrated experimentally and by numerical simulations. For ohmic S/D contacts, the temperature-independent point (ZTC) happens for front gate bias from −2.44 V to −0.61 V (for a back gate VGB changing from −15 V to −30 V respectively). Following other technologies, such as UTBB and FinFET, this point represents the compensation between the threshold voltage decrease and the mobility degradation when increasing the temperature. However, for S/D to channel Schottky contacts, there is no ZTC point and only for this condition the BESOI presents a reconfigurable behavior, i.e., p-type and n-type BESOI behavior can be observed by applying different VGB. The BESOI CMOS inverter built with nickel S/D electrodes was used to confirm the transistor reconfigurability. Therefore, depending on the S/D electrodes material, a reconfigurable device or a ZTC bias point behavior on BESOI MOSFET is observed, which is useful for different applications at the same chip.