Controlled Silicidation of Silicon Nanowires Using Flash Lamp Annealing

Abstract

Among other new device concepts, nickel silicide (NiSi x )-based Schottky barrier nanowire transistors are projected to supplement down-scaling of the complementary metal-oxide-semiconductor (CMOS) technology as its physical limits are reached. Control over the NiSi x phase and its intrusions into the nanowire are essential for superior 1 performance and down-scaling of these devices. Several works have shown control over the phase, but control over the intrusion lengths has remained a challenge. To overcome this, we report a novel millisecond-range flash-lamp-annealing (FLA)-based silicidation process. Nanowires are fabricated on silicon-on-insulator substrates using a top-down approach. Subsequently, Ni silicidation experiments are carried out using FLA. It is demonstrated that this silicidation process gives unprecedented control over the silicide intrusions. Scanning electron microscopy and high-resolution transmission electron microscopy are performed for structural characterization of the silicide. FLA temperatures are estimated with the help of simulations.

Novel Mixed-Dimensional hBN-Passivated Silicon Nanowire Reconfigurable Field Effect Transistors: Fabrication and Characterization

“…Figure 2a shows an optical micrograph of two single nanowirebased devices. 18 The first device is without an hBN dielectric layer, while the second device is capped with a thin hBN layer. AFM analysis is performed on these two devices, and the AFM topography is shown in Figure 2b.…”

“…Height profiles are extracted from multiple AFM scans to determine the thickness of the hBN flakes. Figure a shows an optical micrograph of two single nanowire-based devices . The first device is without an hBN dielectric layer, while the second device is capped with a thin hBN layer.…”

“…The fabrication of source and drain Ni contacts at both ends of the nanowire includes a similar process of EBL patterning, metal deposition using a UHV e-beam evaporation system from BESTEC, and a lift-off process. Flash lamp annealing (FLA) is performed on the substrate after the Ni contact deposition to achieve diffusion of Ni into the nanowire to form the NiSi 2 phase . Ni silicidation in the nanowire creates a heterostructure of NiSi 2 –Si–NiSi 2 forming two Schottky junctions on either side.…”

“…Flash lamp annealing (FLA) is performed on the substrate after the Ni contact deposition to achieve diffusion of Ni into the nanowire to form the NiSi 2 phase. 18 Ni silicidation in the nanowire creates a heterostructure of NiSi 2 −Si−NiSi 2 forming two Schottky junctions on either side. A prior study was conducted to develop a Ni silicidation process of silicon nanowires by rapid thermal annealing (RTA).…”

“…The top-down approach involves the use of a substrate material, which is subjected to successive subtractive procedures to ultimately achieve a nanostructure. The detailed process of silicon nanowire fabrication is described in our previous work 18 and schematically shown in Figure 6. At first, the SOI substrate is cleaned thoroughly in various chemicals, including Piranha solution, acetone, isopropanol (IPA), and deionized (DI) water.…”