电沉积Mo和Mo-Co合金纳米线用于互联电阻的电阻率改性

Achieving historically anticipated improvement in the performance of integrated circuits is challenging,due to the increasing cost and complexity of the required technologies with each new generation.To overcome this limitation,the exploration and development of novel interconnect materials and processes are highly desirable in the microelectronics field.Molybdenum(Mo)is attracting attention as an advanced interconnect material due to its small resistivity size effect and high cohesive energy;however,effective processing methods for such materials have not been widely investigated.Here,we investigate the electrochemical behavior of ions in the confined nanopores that affect the electrical properties and microstructures of nanoscale Mo and Mo-Co alloys prepared via template-assisted electrodeposition.Additives in an electrolyte allow the deposition of extremely pure metal materials,due to their interac-tion with metal ions and nanopores.In this study,boric acid and tetrabutylammonium bisulfate(TBA)were added to an acetate bath to inhibit the hydrogen evolution reaction.TBA accelerated the reduction of Mo at the surface by inducing surface conduction on the nanopores.Metallic Mo nanowires with a 130 nm diameter synthesized through high-aspect-ratio nanopore engineering exhibited a resistivity of(63.0±17.9)μΩcm.We also evaluated the resistivities of Mo-Co alloy nanowires at various compo-sitions toward replacing irreducible conventional barrier/liner layers.An intermetallic compound formed at a Mo composition of 28.6 at%,the resistivity of the Mo-Co nanowire was(58.0±10.6)μΩcm,indicat-ing its superior electrical and adhesive properties in comparison with those of conventional barriers such as TaN and TiN.Furthermore,density functional theory and non-equilibrium Green's function calcula-tions confirmed that the vertical resistance of the via structure constructed from Mo-based materials was 21%lower than that of a conventional Cu/Ta/TaN structure.

A MoS_2 nanocatalyst with surface-enriched active sites for the heterogeneous transfer hydrogenation of nitroarenes

A highly efficient and reusable plane‐curved and interlayer‐expanded MoS2nanocatalyst with increased exposure of active sites was prepared.The catalyst was used for the heterogeneous hydrogen transfer reaction of nitroarenes with hydrazine monohydrate as a reductant under mild reaction conditions without pressure and base,which was different from other hydrogen transfer systems that require the presence of a base(e.g.,propan‐2‐ol/KOH).The sandwiching of carbon between the MoS2nanosheets increased the distance between the layers of MoS2and exposed more Mo sites,resulting in superior catalytic performance compared with that of bulk MoS2catalyst.The active hydrogen(H*)generated from N2H4could directly transfer to the–NO2groups of nitrobenzene to form aniline followed by N2emission,which was confirmed by detecting the gas emission with mass spectrometry during the decomposition of hydrazine or the co‐existence of nitrobenzene and hydrazine.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

Evaluation of the diagnostic and therapeutic utility of retrograde through-the-scope balloon enteroscopy and single-balloon enteroscopy

BACKGROUND Retrograde single balloon enteroscopy(SBE)is a minimally invasive procedure which is less frequently performed compared with antegrade SBE.There are few studies on the retrograde through-the-scope enteroscopy(TTSE),a novel technique for evaluation of the small bowel.AIM To compare the clinical utility and safety of retrograde TTSE with retrograde SBE.METHODS Clinical data and complications of retrograde TTSE(2014-2018)and retrograde SBE(2011-2018)performed in a community hospital were reviewed and presented as mean±SD or frequency(%)and compared using proper statistical tests.Technical success was defined as insertion of the enteroscope>20 cm beyond ileocecal valve.RESULTS Data obtained from 54 retrograde SBE in 49 patients and 27 retrograde TTSE in 26 patients were studied.The most common indication for retrograde enteroscopy was iron deficiency anemia(41 patients)followed by gastrointestinal bleeding(37 patients),and chronic diarrhea(7 patients).The duration of retrograde SBE procedure(91.9±34.2 min)was significantly longer compared with retrograde TTSE(70.5±30.7 min)(P=0.04).Technical success was comparable in TTSE[23/27(85.2%)]and SBE[41/54(75.9%)(P=0.33)].The mean depth of insertion beyond the ileocecal valve in retrograde SBE(92.5±70.0 cm)tended to be longer compared with retrograde TTSE(64.6±49.0 cm)(P=0.08).No complication was observed in this study.CONCLUSION Both retrograde TTSE and retrograde SBE are feasible and safe.Retrograde TTSE takes a shorter time and has a comparable technical success with SBE.TTSE has a lower capacity of small bowel insertion.

Electrical resistivity evolution in electrodeposited Ru and Ru-Co nanowires

Nanoscale ruthenium(Ru)-based materials are promising replacements for existing multilayered Cu interconnects in integrated circuits.However,it is not easy to apply the results of previously reported studies directly to the electrochemical damascene process because the previous studies have mainly focused on thin flms by dry deposition.Here,we report the electrical resistivity and microstructure of electrodeposited Ru nanowires.We estimate that the resistivity value of a 10 nm diameter Ru nanowire to be71.6μΩcm after analyzing the resistivity values of individual nanowires with various diameters.Furthermore,we investigate the electrical properties of Ru_(x)Co_(1-x)nanowires where x is 0.04–0.99 at.%as possible replacements of the current Ta N barrier structures.Over the entire composition range,the resistivity values of alloys are much lower than that of the conventional Ta N.Additionally,Ru and Ru-alloy nanowires surrounded by dielectric silica are thermally stable after 450°C heat treatment.Therefore,the nanoscale Ru and Ru-Co alloys possessing low resistivity values can be candidates for the interconnect and barrier materials,respectively.