title: Sensing with Advanced Computing Technology: Fin Field-Effect Transistors with High-k Gate Stack on Bulk Silicon.
abstract: Field-effect transistors (FETs) form an established technology for sensing applications. However, recent advancements and use of high-performance multigate metal-oxide semiconductor FETs (double-gate, FinFET, trigate, gate-all-around) in computing technology, instead of bulk MOSFETs, raise new opportunities and questions about the most suitable device architectures for sensing integrated circuits. In this work, we propose pH and ion sensors exploiting FinFETs fabricated on bulk silicon by a fully CMOS compatible approach, as an alternative to the widely investigated silicon nanowires on silicon-on-insulator substrates. We also provide an analytical insight of the concept of sensitivity for the electronic integration of sensors. N-channel fully depleted FinFETs with critical dimensions on the order of 20 nm and HfO2 as a high-k gate insulator have been developed and characterized, showing excellent electrical properties, subthreshold swing, SS ∼ 70 mV/dec, and on-to-off current ratio, Ion/Ioff ∼ 10(6), at room temperature. The same FinFET architecture is validated as a highly sensitive, stable, and reproducible pH sensor. An intrinsic sensitivity close to the Nernst limit, S = 57 mV/pH, is achieved. The pH response in terms of output current reaches Sout = 60%. Long-term measurements have been performed over 4.5 days with a resulting drift in time δVth/δt = 0.10 mV/h. Finally, we show the capability to reproduce experimental data with an extended three-dimensional commercial finite element analysis simulator, in both dry and wet environments, which is useful for future advanced sensor design and optimization.
authors: †Nanoelectronic Devices Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors: Sara
authors: S
authors: Rigante
authors: ‡Department of Electrical, Management and Mechanical Engineering, University of Udine, 33100 Udine, Italy.
authors: Paolo
authors: P
authors: Scarbolo
authors: §Department of Physics, University of Basel, 4003 Basel, Switzerland.
authors: Mathias
authors: M
authors: Wipf
authors: §Department of Physics, University of Basel, 4003 Basel, Switzerland.
authors: Ralph L
authors: RL
authors: Stoop
authors: ∥Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen, Switzerland.
authors: Kristine
authors: K
authors: Bedner
authors: †Nanoelectronic Devices Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors: Elizabeth
authors: E
authors: Buitrago
authors: †Nanoelectronic Devices Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors: Antonios
authors: A
authors: Bazigos
authors: †Nanoelectronic Devices Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors: Didier
authors: D
authors: Bouvet
authors: §Department of Physics, University of Basel, 4003 Basel, Switzerland.
authors: Michel
authors: M
authors: Calame
authors: §Department of Physics, University of Basel, 4003 Basel, Switzerland.
authors: Christian
authors: C
authors: Schönenberger
authors: †Nanoelectronic Devices Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors: Adrian M
authors: AM
authors: Ionescu
keywords: Fin field-effect transistor sensor; FinFET; ISFET; high-k dielectric; long-term stability; low power; pH sensing; sensing integrated circuits