Effects of different oxidizers on the W-CMP performance

Seo, Yong-Jin; Lee, Woo-Sun

doi:10.1016/j.mseb.2004.12.064

Cited by 30 publications

(26 citation statements)

References 8 publications

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“…The presence of KIO 3 in W CMP slurry along with H 2 O 2 was found to produce a nonstoichiometric duplex of WO 2 /WO 3 leading to low removal rates due to the increasing hardness of the oxide film with the reduction in the oxygen content, and hence the presence of WO 2 in the surface film leads to lower removal rates in case of KIO 3 [29].…”

Section: Potassium Permanganate Dichromates and Iodatementioning

confidence: 98%

“…Under oxidizing condition, tungsten has much better passivation characteristics. More OXIDIZERS specifically, native passivating film such as WO 3 and FeWO 4 can be formed very rapidly during CMP [29,13]. In addition to serving as an oxidizer, ferric ions have also been utilized as catalysts or cooxidizers for hydrogen peroxide.…”

Section: Ferric Nitratementioning

confidence: 99%

“…In addition to serving as an oxidizer, ferric ions have also been utilized as catalysts or cooxidizers for hydrogen peroxide. Seo and coworkers [29] studied a slurry containing ferric nitrate and hydrogen peroxide and found the slurry gives high removal rates due to synergistic interaction between ferric ions and hydrogen peroxide. It was also found that the formation of FeWO 4 film has a passivating effect.…”

Section: Ferric Nitratementioning

confidence: 99%

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Key Chemical Components in Metal CMP Slurries

Cheemalapati

Keleher

2007

Microelectronic Applications of Chemical Mechanical Planarization

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Chemical-mechanical planarization (CMP) slurries can be classified into two general categories according to their applications: metal CMP slurry and nonmetal CMP slurry. Two most important metals incorporated into IC chip manufacturing via CMP are W and Cu. Depending upon integration schemes, a metal CMP slurry may or may not carry out the function of removing the film(s) immediately below the overburden metal such as cap, adhesion, and barrier layers. For tungsten CMP, a single-step slurry is typically used to remove both excess tungsten and its barrier/adhesion layer. For copper CMP, after the removal of copper, a subsequent barrier removal step is often required. This chapter reviews the basic requirements for the key components found in common metal slurries.It is generally understood that a metal CMP slurry chemically modifies the surface to be polished and yields a softer and porous complex layer, which is then removed by mechanical force in the process. Although these metals may differ in their physical and chemical properties, the underlying principle for the design of slurries is the same. A production-worthy metal CMP slurry must address several issues, such as material removal rate (MRR), within-wafer nonuniformity (WIWNU), step height reduction efficiency, dishing/erosion, minimum ILD loss, corrosion, scratching, slurry residue, and other surface defects. Typical metal CMP slurry may contain an oxidant, a chelating agent, abrasive particles, a surfactant, and other additives. These components must work in concert to produce adequate material removal rate, high planarization efficiency, and Microelectronic Applications of Chemical Mechanical Planarization, Edited by Yuzhuo Li

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Section: Potassium Permanganate Dichromates and Iodatementioning

confidence: 98%

Section: Ferric Nitratementioning

confidence: 99%

Section: Ferric Nitratementioning

confidence: 99%

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Key Chemical Components in Metal CMP Slurries

Cheemalapati

Keleher

2007

Microelectronic Applications of Chemical Mechanical Planarization

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“…A typical W CMP process consists of several polishing materials: W, W liner (Ti and/or TiN), and Oxide [45][46][47]. In some unique W CMP applications, the process may involve the removal or stoping of other materials such as for SiN and poly-Si.…”

Section: Influence Of Processing Temperaturementioning

confidence: 99%

Defects Observed on the Wafer after the CMP Process

LeFevre

2007

Microelectronic Applications of Chemical Mechanical Planarization

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“…In competing theories, Kneer suggests that transgranular fracture assisted by inter-granular corrosion under high polishing down force, 6 while Steina et al suggest that dissolution of tungsten oxides is the primary non-mechanical W removal mechanism. 7 Further, variables such as oxidizer types, 8 concentration of chemicals and abrasives in the slurry 9 were studied, producing insights into the W CMP mechanism from the electrochemical perspective. Other areas of research considered pad asperity 10 and W grain morphologies.…”

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confidence: 99%

Impact of Film Morphology on Chemical Mechanical Polishing of Tungsten

Shen

Fung

et al. 2016

ECS J. Solid State Sci. Technol.

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This study investigated the effects of tungsten (W) film morphology on the chemical mechanical polishing (CMP) of W. Chemical vapor deposited (CVD) W films with two distinctively different grain sizes were used for comparison. During polishing, W film thickness and optical reflectance, friction, and pad temperature were monitored in-situ. It was found that larger-grained W film took longer to pass the initial low removal rate stage. By correlating four different sensor signals, comparing friction dependency on film morphology, in slurry vs. DIW, it was concluded that W CMP comprises three main stages. First is the low rate initiation stage: grain is being partially planarized, reflectance increases, friction decreases. Second is the transition stage: rate is ramping, grain becomes fully planarized, optical reflectance reaches maximum, and friction becomes minimal followed by a significant rise caused by formation of tungsten oxide passivation layer on the planarized W surface. Third is the high and constant rate stage: passivation and removal occur in a repetitive cycle, friction is high and stable, optical reflectance changes as polishing reaches different film depths. In all three stages, pad temperature increases continuously as friction-induced heat dissipates, with the rate of temperature increase following that of friction magnitude. Metal CMP has enabled integrated circuit (IC) scaling as summarized in Table I. Depending on metal types and their different reactivity, different deposition methods are used. For example, aluminum (Al), a highly reactive metal, is deposited by high-temperature physical vapor deposition (PVD); whereas copper (Cu) as a noble metal is deposited by electrochemical plating (ECP) on top of a PVD Cu seed layer; W is deposited by CVD as its precursors and reaction by-product are in the gaseous phase. CVD cobalt is emerging as a replacement for Cu in back-end-of-line interconnects as it can fill much smaller line widths. Given their superior gap fill ability, CVD and atomic layer deposition (ALD) will become more common as IC scaling continues to 10 nm and beyond.CVD W and W CMP are widely used in IC manufacturing. W CMP was first introduced in 1995 as contact metal and enabled 0.35 μm technology yield and defect readiness.1 More recently, CVD W and W CMP enabled FinFET replacement metal gate (RMG) 2 when PVD Al could no longer fill in the small gate in the 3D structure. In addition to contact metal and gate metal in logic devices, W is widely used in memory, where 3D NAND involves many steps of CVD W and W CMP. CVD W grain size and crystalline orientation are dependent on many parameters, including the sub-layer films, ALD W nucleation, and CVD W deposition precursors and deposition temperature.3 For instance, CVD W is mostly dominated by alpha phase with (110) orientation >80% at 400• C, with some portion of beta phase (114) if CVD W temperature is higher.4 Different types of W applications have different sub-layers and deposition conditions. For CVD W used in contact, sub-layers in...

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Effects of different oxidizers on the W-CMP performance

Cited by 30 publications

References 8 publications

Key Chemical Components in Metal CMP Slurries

Key Chemical Components in Metal CMP Slurries

Defects Observed on the Wafer after the CMP Process

Impact of Film Morphology on Chemical Mechanical Polishing of Tungsten

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