Cu dry-fill on CVD Ru liner for advanced gap-fill and lower resistance

Ishizaka, Tadahiro; Gomi, Atsushi; Kato, Takara; Sakuma, Takashi; Yokoyama, Osamu; Yasumuro, C.; Toshima, Hiroyuki; Mizusawa, Yasushi; Hatano, Tatsuo; Han, Chao; Hara, M.

doi:10.1109/iitc.2011.5940338

Cited by 8 publications

(7 citation statements)

References 1 publication

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“…Device fabrication today relies on “top-down” approaches, requiring multiple lithography and etch steps which can result in edge placement errors and serve as a process bottleneck as device dimensions shrink. Thus, there is great attention placed on selecting new materials and developing new fabrication schemes, including replacements for Cu interconnect structures. − …”

Section: Introductionmentioning

confidence: 99%

“…As Cu metal line widths shrink and approach the electron mean free path, the linear relationship between resistivity and dimensions breaks down, leading to performance and reliability issues. , Several strategies are currently being implemented or investigated for addressing this challenge. One strategy is to replace the Ta liners used for Cu interconnects with alternative metal liners such as Ru or Co because they have better Cu wettability, which is important for improved gap fill, as well as lower resistance. − Another strategy is to replace Cu interconnects with another metal. In this case, Co, W, and Ru , have been studied because of their lower resistance-size effects.…”

Section: Introductionmentioning

confidence: 99%

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Area-Selective Atomic Layer Deposition Assisted by Self-Assembled Monolayers: A Comparison of Cu, Co, W, and Ru

et al. 2019

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Area-selective atomic layer deposition (AS-ALD) is a promising "bottom-up" alternative to current nanopatterning techniques. Self-assembled monolayers (SAM) have been successfully employed as deactivating agents to achieve AS-ALD. In this work, the formation of octadecylphosphonic acid (ODPA) SAMs is studied on four technologically important metal substrates: Cu, Co, W, and Ru. The SAM quality is shown to be dependent on temperature, solvent, and the nature of the substrate. The blocking ability of the ODPA-treated substrates is evaluated using ZnO and Al 2 O 3 model ALD processes. Spectroscopic analyses reveal that ODPA-assisted ALD blocking can be achieved to varying degrees of success on each metal. ODPAprotected W showed >90% selectivity after 32 nm ZnO and 8 nm Al 2 O 3 ALD, exhibiting the best blocking overall. For all substrates, ZnO ALD proved consistently easier to block than Al 2 O 3 , indicating the importance of precursor chemistry. Additionally, we show that the self-correcting process previously reported for Cu using an acetic acid etchant can be extended to Co. This process improves selective deposition of Al 2 O 3 on patterned Co/SiO 2 with feature sizes as small as 25 nm. Additional studies reveal that feature size and density affect the apparent selectivity in SAM-based AS-ALD, highlighting the importance of such considerations in future process developments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Area-Selective Atomic Layer Deposition Assisted by Self-Assembled Monolayers: A Comparison of Cu, Co, W, and Ru

et al. 2019

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“…Degas/Pre-clean, CVD Ru and PVD Cu dry-fill processes are described elsewhere [3]. ALD TaN barriers where deposited at 350C using TBTEMTa and NH3 at 350C and 0.07nm/cycle and 11 cycles/min.…”

Section: Methodsmentioning

confidence: 99%

“…So far, ALD barriers have not delivered on their promise as PVD Ta flash and/or PVD Cu seed layers were still needed to provide a good barrier-Cu interface. CVD Ru has been demonstrated a powerful replacement for PVD Ta liner / PVD Cu seed due to its excellent adhesion to Cu, conformality and thickness control, enabling excellent Cu wet-ability and fill [3,4,5], as well as up to 20% lower line resistance due to larger Cu grain size on Ru [3,4]. In this paper we present, for the first time, integration of advanced ALD TaN-based barriers, CVD Ru liner and PVD Cu dry-fill.…”

Section: Introductionmentioning

confidence: 95%

Integration of ALD barrier and CVD Ru liner for void free PVD Cu reflow process on sub-10nm node technologies

Yu¹,

Oie²,

F³

et al. 2014

IEEE International Interconnect Technology Conference

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Cu-fill extendability is demonstrated with a novel integration scheme using clustered ALD barrier, CVD Ru liner and PVD Cu dry-fill processes. ALD barrier films were developed and integrated with a 2nm CVD-Ru (replacing the traditional PVD Ta and PVD Cu seed), and a single-step PVD Cu dry-fill process for bottom-up via and trench fill. Line resistance and barrier integrity data complement the Cu-fill performance.

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“…11 Cu has excellent wetting on Ru, which could enable reflow PVD Cu to fill the whole structure without ECP process. 12,13 Ru can also facilitate direct ECP Cu process on its surface without PVD Cu seed. 14 Cobalt (Co) is another promising liner that is under active evaluation.…”

mentioning

confidence: 99%

Mechanism of Co Liner as Enhancement Layer for Cu Interconnect Gap-Fill

Zhang

Nogami

et al. 2013

J. Electrochem. Soc.

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Cu gap-fill is enhanced by replacing the conventional Ta liner with a Co liner in a 22 nm width interconnect structure. The improvement with Co liner seen at the line-end area is attributed to a better resputtered Cu seed profile, which is thicker and exhibits no agglomeration compared to that on Ta liner. The mechanism of Co offering better Cu seed coverage than Ta was further studied and determined to be associated with its better wetting and higher sticking coefficient with Cu during the resputtering process. Similar gap-fill performance was also demonstrated with a reflow Cu seed process. The initial highly conformal Cu seed coverage profile on Co helps ensure a uniform Cu reflow process within the interconnect structure, therefore providing better top-open dimension for electrochemical plating process compared to reflow Cu seed on Ta. . This paper is part of the JES Focus Issue on Electrochemical Processing for Interconnects.As advanced microelectronics move toward the 20 nm node and beyond, back-end of line (BEOL) interconnects are shrinking to sub-80 nm pitch dimensions. 1 Driving toward smaller pitch encounters numerous integration challenges, including Cu metallization. From a circuit performance perspective, one particular issue is the increase of Cu line resistance (R). As metal line widths approach and even become smaller than the electron mean free path within Cu, line resistance no longer linearly scales with dimension. Instead, Cu resistivity starts to increase dramatically due to the increased electron surface scattering. 2 The subsequent increase of the RC (resistance × capacitance) delay within the interconnect circuit will negatively impact the circuit speed. Meanwhile, higher R will also consume more energy and complicate heat dissipation, both of which are not ideal for low-power devices.Besides metallization-related performance challenges, another critical issue in these fine lines is reliability, particularly electromigration (EM). It is increasingly difficult to control microstructure within the metal line and as well as interface qualities at fine dimension. Cu microstructure does not easily form a bamboo grain structure by grain growth from electrochemical plated (ECP) Cu overburden in sub-40 nm metal widths. 3 Connected grain boundaries within polycrystalline Cu lines could act as fast Cu diffusion paths. 4 Meanwhile, the other two critical interfaces, Cu-liner and Cu-cap, need to maintain their strong bonding for EM extendibility. 5,6 But before these performance and reliability issues can even be considered, first these sub-40 nm wide dual-damascene structures must be metallized without Cu-voiding defects. The conventional approach for metallization is to first deposit a layer of barrier and liner (usually TaN and Ta, correspondingly), followed by a Cu seed. The coated wafer will go into a plating bath with ECP Cu nucleation initiated on the PVD Cu seed surface first, and then be filled bottom-up with Cu ECP process. Bottom-up growth results from faster ECP Cu growth at the feature bo...

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Cu dry-fill on CVD Ru liner for advanced gap-fill and lower resistance

Cited by 8 publications

References 1 publication

Area-Selective Atomic Layer Deposition Assisted by Self-Assembled Monolayers: A Comparison of Cu, Co, W, and Ru

Area-Selective Atomic Layer Deposition Assisted by Self-Assembled Monolayers: A Comparison of Cu, Co, W, and Ru

Integration of ALD barrier and CVD Ru liner for void free PVD Cu reflow process on sub-10nm node technologies

Mechanism of Co Liner as Enhancement Layer for Cu Interconnect Gap-Fill

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