Abstract
In this paper, the compressive stress of pristine and coated vertically-aligned (VA) multi-walled (MW) carbon nanotube (CNT) pillars were investigated using flat-punch nano-indentation. VA-MWCNT pillars of various diameters (30–150 µm) grown by low-pressure chemical vapor deposition on silicon wafer. A conformal brittle coating of niobium-titanium-nitride with high superconductivity temperature was deposited on the VA-MWCNT pillars using atomic layer deposition. The coating together with the pillars could form a superconductive vertical interconnect. The indentation tests showed foam-like behavior of pristine CNTs and ceramic-like fracture of conformal coated CNTs. The compressive strength and the elastic modulus for pristine CNTs could be divided into three regimes of linear elastic, oscillatory plateau, and exponential densification. The elastic modulus of pristine CNTs increased for a smaller pillar diameter. The response of the coated VA-MWCNTs depended on the diffusion depth of the coating in the pillar and their elastic modulus increased with pillar diameter due to the higher sidewall area. Tuning the material properties by conformal coating on various diameter pillars enhanced the mechanical performance and the vertical interconnect access (via) reliability. The results could be useful for quantum computing applications that require high-density superconducting vertical interconnects and reliable operation at reduced temperatures.
Highlights
Carbon nanotube (CNT) based structures have attracted widespread scientific interest due to their exceptional mechanical and electrical performance rendering them as promising candidates for advanced applications on various scales [1]
Poelma et al [40] investigated the compressive strength of CNT arrays coated with SiC using the low-pressure chemical vapor deposition (LPCVD) process
Deposition of NbTiN directly on bare and oxidized Si substrate shows a sharp feature at 520 cm−1 and a smaller feature around 970 cm−1 which originate from the crystalline Si substrate
Summary
Carbon nanotube (CNT) based structures have attracted widespread scientific interest due to their exceptional mechanical and electrical performance rendering them as promising candidates for advanced applications on various scales [1]. CNTs are the strongest and stiffest materials in terms of tensile strength, but not nearly as strong under compression Because of their hollow structure and high aspect ratio, individual tubes tend to undergo buckling when placed under compressive, torsional, or bending stress [16]. Poelma et al [40] investigated the compressive strength of CNT arrays coated with SiC using the low-pressure chemical vapor deposition (LPCVD) process. In both publications, the material properties could be accurately tuned using different coating thicknesses and the compressive strength increased as a function of the coating thickness. AVA-M-MWWCCNNTTPPillilalrarGGrorwowththwwitihthLLPPCCVVDD nannaonGpoGaprorartworitcwitlchetlhseo,s,afoanfCndCNdaNTacTacoaronbrnboaonanssissoloiiulcuirocrconcene..wTwTahhafeeeferbbraannrrerreeiieeeddrrssllaatthyyherererreeepprmrmeevavaeieinnnnttsiisnnttghghrereeeddddiiiifeefffnnuuttssssi::oionanaobobfafatrhtrrhrieeieercrcalatalatayalyyelyser,trs,ticniacntatoattolatyhltysehtset silsiicliocnonsusbusbtsrtartaeteaannddeennaabblelessththeettrraannssiittiioonn mmeettaall ccaattaallyysstt ffiillmm ttoo bbrreeaakkuuppiinnttoonnaannooppaartritciclelessininstsetaedad ofoffofromrminigngananagagglgolmomerearatitoionn. Neexxt,t,MMWWCCNNTTppiillllaarrss aarree ggrroowwnn bbyy LLPPCCVVDDiinnaaccoommmmeercrciaial lddepepoosistiitoinon syssytsetmem(B(lBalcakckMMagaigcicPrPor,oA, Aixitxrtorno,nH, Herezrozgoegnernartaht,hG, Geremrmanany)y.).TThheeCCNNTTs saraeregrgorwownnatataatetmemppereartauturereof 65o0f ◦6C50u°sCinugsianggaasgflaoswflomwixmtuixrteuoref o7f0070s0ccsmccmhyhdyrdorgoegnenovoevrer5050scscccmmaacceettyylleennee((HH22//CC22HH22))aatt8800mmbabrar fofro1r010mmini.nutes
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