Unraveling structural and compositional information in 3D FinFET electronic devices.

Non-planar Fin Field Effect Transistors (FinFET) are already present in modern devices. The evolution from the well-established 2D planar technology to the design of 3D nanostructures rose new fabrication processes, but a technique capable of full characterization, particularly their dopant distribution, in a representative (high statistics) way is still lacking. Here we propose a methodology based on Medium Energy Ion Scattering (MEIS) to address this query, allowing structural and compositional quantification of advanced 3D FinFET devices with nanometer spatial resolution. When ions are backscattered, their energy losses unfold the chemistry of the different 3D compounds present in the structure. The FinFET periodicity generates oscillatory features as a function of backscattered ion energy and, in fact, these features allow a complete description of the device dimensions. Additionally, each measurement is performed over more than thousand structures, being highly representative in a statistical meaning. Finally, independent measurements using electron microscopy corroborate the proposed methodology.

Room temperature synthesis of HfO2/HfO x heterostructures by ion-implantation.

Implantation of Hf films with oxygen ions is shown to be an effective means of fabricating high-quality HfO2/HfO x heterostructures at room temperature, with the layer composition and thicknesses determined by the ion energy and fluence. Implantation with 3 keV O+ ions to a fluence of 1 × 1017 ions cm-2 produces a polycrystalline (monoclinic-) HfO2 layer extending from the surface to a depth of ∼12 nm, and an underlying graded HfO x layer extending an additional ∼7 nm, while implantation with 6 keV O to a similar fluence produces a near-stoichiometric surface layer of 7 nm thickness and a graded substoichiometric layer extending to depth of ∼30 nm. These structures are shown to be broadly consistent with oxygen range data but more detailed comparison with dynamic Monte Carlo simulations suggests that the near-surface region contains more oxygen than expected from collisional processes alone. The bandgap and dielectric strength of the HfO2 layer produced by 3 keV; 1 × 1017 ions cm-2 implant is shown to be indistinguishable from those of an amorphous film deposited by atomic layer deposition at 200 °C. The utility of these layers is demonstrated by studying the resistive switching properties of metal-oxide-metal test structures fabricated by depositing a top metal contact on the implanted film. These results demonstrate the suitability of ion-implantation for the synthesis of functional oxide layers at room temperature.