Metal induced charge transfer doping in graphene-ruthenium hybrid interconnects

Achra, Swati; Wu, Xiangyu; Trepalin, Vadim; Nuytten, Thomas; Ludwig, Jonathan; Afanasʼev, Valeri; Brems, Steven; Sorée, Bart; Tőkei, Zsolt; Heyns, Marc; Asselberghs, Inge

doi:10.1016/j.carbon.2021.07.070

Cited by 14 publications

(7 citation statements)

References 78 publications

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“…The intensity of the defect-related D band ( I D ) located at ∼1350 cm –1 is negligible, demonstrating its high crystalline quality. The intensity ratio of 2D and G bands ( I 2D / I G ) is calculated as 1.55, which is lower than that of the typical monolayer graphene (∼2) transferred onto the dielectric substrates. , As shown in Figure S3, an identical graphene layer transferred onto the sapphire substrate exhibits an increased I 2D / I G of 2.26, and this difference might be induced by the charge transfer between graphene and metallic substrates, which also appeared in our previous work with the Au film deposited on the monolayer graphene …”

Section: Resultsmentioning

confidence: 49%

“…The intensity ratio of 2D and G bands (I 2D / I G ) is calculated as 1.55, which is lower than that of the typical monolayer graphene (∼2) transferred onto the dielectric substrates. 28,29 As shown in Figure S3, an identical graphene layer transferred onto the sapphire substrate exhibits an increased I 2D /I G of 2.26, and this difference might be induced by the charge transfer between graphene and metallic substrates, 30 which also appeared in our previous work with the Au film deposited on the monolayer graphene. 31 Based on the AlGaN epitaxial processes (see the Methods), we design three types of epitaxial structures for comparison.…”

Section: ■ Results and Discussionmentioning

confidence: 51%

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Van der Waals Epitaxy of c-Oriented Wurtzite AlGaN on Polycrystalline Mo Substrates for Enhanced Heat Dissipation

Chen

Zang

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

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The epitaxy of III-nitrides on metallic substrates is competitive due to the advantages of vertical carrier injection, enhanced heat dissipation, and flexible application in various IIInitride-based devices. However, the serious lattice mismatch, atom diffusion, and interface reaction under the rigorous growth conditions have caused enormous obstacles. Based on the thermal and chemical stability of the graphene layer, we propose the van der Waals epitaxy of c-oriented wurtzite AlGaN on the polycrystalline Mo substrate by high-temperature metal−organic chemical vapor deposition. The insertion of a graphene layer interrupts the chaotic epitaxial relationship between the polycrystalline metal and epilayers, resulting in the single-crystalline orientation along the wurtzite (0002) plane and residual stress release in AlGaN because of the weak van der Waals interaction. We also demonstrate that the epitaxy of AlGaN on Mo metal possesses enhanced heat dissipation ability, in which the epilayer temperature is controlled at only 28.7 °C by the heating of a ∼54 °C hot plate. The heat dissipation enhancement for the present epitaxial structures provides a desirable strategy for the fabrication of efficient ultraviolet devices with excellent stability and lifetime.

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Section: Resultsmentioning

confidence: 49%

Section: ■ Results and Discussionmentioning

confidence: 51%

Van der Waals Epitaxy of c-Oriented Wurtzite AlGaN on Polycrystalline Mo Substrates for Enhanced Heat Dissipation

Chen

Zang

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

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“…Then, the graphene on SiO 2 was measured by Raman spectroscopy, which could also clearly reveal a 2D peak, indicating that the diffusion of carbon into Co had grown as graphene at the bottom. Figure S2 benchmarks the temperature of graphene growth on various interconnect metal wires in our work and previous studies. ,− ,− Our report demonstrates the lowest process temperature for graphene growth and the ability to directly synthesize graphene all around a Co wire. These results indicate that HW-CVD could effectively meet the requirements for direct growth and thermal budgets in BEOL.…”

supporting

confidence: 57%

Graphene-All-Around Cobalt Interconnect with a Back-End-of-Line Compatible Process

Kuo,

Zhu,

Chiu

et al. 2024

Nano Lett.

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The graphene-all-around (GAA) structure has been verified to grow directly at 380 °C using hot-wire chemical vapor deposition, within the thermal budget of the back end of the line (BEOL). The cobalt (Co) interconnects with the GAA structure have demonstrated a 10.8% increase in current density, a 27% reduction in resistance, and a 36 times longer electromigration lifetime. X-ray photoelectron spectroscopy and density functional theory calculations have revealed the presence of bonding between carbon and Co, which makes the Co atom more stable to resist external forces. The ability of graphene to act as a diffusion barrier in the GAA structure was confirmed through time-dependent dielectric breakdown measurement. The Co interconnect within the GAA structure exhibits enhanced electrical properties and reliability, which indicates compatibility applications as next-generation interconnect materials in CMOS BEOL.

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“…The weak intensity of D band proves less defects in graphene, and it has a monolayer nature according to the intensity ratio of 2D to G bands (I 2D / I G = 1.2), this value is lower than the previously reported graphene transferred onto dielectric substrates (∼2) due to the carrier doping of graphene by the Mo metal. 23,24 In order to further confirm the layer number of graphene, it is transferred onto the dielectric sapphire, and the Raman spectra in Figure S1b shows an increased I 2D /I G value of 2.49. The atomic force microscope (AFM) image of graphene on the Mo substrate shows several wrinkles, as marked by the white dashed lines, which might be generated during the growth and wet transfer processes, corresponding root-mean-square roughness (R q ) is 3.23 nm (see Figure S2).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

AlGaN UV Detector with Largely Enhanced Heat Dissipation on Mo Substrate Enabled by van der Waals Epitaxy

Chen

Zang

Ben

et al. 2022

Crystal Growth & Design

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The epitaxy of AlGaN on metallic substrates exhibits numerous advantages including flexibility, vertical carrier injection, and enhanced heat dissipation for optoelectronic devices; however, there are still many challenges for the growth of AlGaN according to the serious interfacial reaction and lattice mismatch by conventional epitaxial techniques. In this work, the c-oriented AlGaN is grown on polycrystalline Mo substrate by van der Waals (vdWs) epitaxy with graphene as the insertion layer. A hightemperature annealed AlN is deposited as the nucleation layer, which optimizes the crystalline quality of following AlGaN. The isolation effect of the graphene insertion layer results in a good epitaxial interface, which suppresses the atoms diffusion and chemical reaction, demonstrating by the theoretical calculation of high energy barriers for Al/Mo atoms penetrating through graphene insertion layer. The ultraviolet (UV) detector is fabricated by further growing a n-AlGaN layer as the photosensitive absorber, whose responsivity (1.7 × 10 −3 A W −1 ) is comparable with that fabricated on conventional sapphire. Even better, the UV detector on the Mo substrate possesses enhanced heat dissipation ability due to its higher thermal conductivity, and the temperature elevation after consistently applying a drive voltage largely decreases by 50%. This work enlightens the growth of AlGaN materials and fabrication of high-power/high-voltage optoelectronic devices on polycrystalline metallic substrates by the mean of vdWs epitaxy.

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Metal induced charge transfer doping in graphene-ruthenium hybrid interconnects

Cited by 14 publications

References 78 publications

Van der Waals Epitaxy of c-Oriented Wurtzite AlGaN on Polycrystalline Mo Substrates for Enhanced Heat Dissipation

Van der Waals Epitaxy of c-Oriented Wurtzite AlGaN on Polycrystalline Mo Substrates for Enhanced Heat Dissipation

Graphene-All-Around Cobalt Interconnect with a Back-End-of-Line Compatible Process

AlGaN UV Detector with Largely Enhanced Heat Dissipation on Mo Substrate Enabled by van der Waals Epitaxy

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