Electrochemical investigation of the roles of oxyanions in chemical–mechanical planarization of tantalum and tantalum nitride

Sulyma, C. M.; Pettit, C.M.; Surisetty, C.; Babu, S. V.; Roy, D.

doi:10.1007/s10800-011-0262-7

Cited by 12 publications

(8 citation statements)

References 47 publications

(111 reference statements)

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“…For both Ru and Cu, a nearly linear correlation is observed between the values of i corr and those of the RRs measured in solutions I-III; this confirms the active roles of electrochemically promoted material removal in these specific cases. 60 On the other hand, for both Ru and Cu, the polish rates measured in solution IV fall outside the electrochemical correlation trends of the RRs with respect to i corr . This indicates that the chemical components of Ru-and Cu-CMP in solution IV are not strictly controlled by electrochemical steps.…”

Section: Corrosion Characteristics and Surface Reactions Ofmentioning

confidence: 83%

Investigation of Percarbonate Based Slurry Chemistry for Controlling Galvanic Corrosion during CMP of Ruthenium

Türk¹,

Rock²,

Amanapu

et al. 2013

ECS J. Solid State Sci. Technol.

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Chemical mechanical planarization (CMP) of Ru barrier lines is expected to become a critical processing step in the fabrication of the new interconnect-structures. However, due to its noble metal characteristics, Ru induces galvanic corrosion in its adjacent Cu lines in the wet CMP environment, and resists chemical surface modifications that are necessary to support CMP. The present work reports a slurry formulation to address these challenges of Ru-CMP, and explores the considerations for residual Cu removal using the same slurry. This alkaline (pH = 10) slurry with colloidal silica abrasives uses sodium percarbonate as an oxidizer/complexing agent in the CMP of both Ru and Cu. L-ascorbic acid is employed as a surface modifier to regulate the material removal rates of CMP, and benzotriazole is used to control galvanic corrosion of the Ru-Cu couple. With this slurry, wafer polish rates of ∼10 and ∼80 nm min−1 are measured for Ru and Cu, respectively, resulting in defect-free processed samples. Electrochemical measurements of open circuit potentials, potentiodynamic polarization and impedance spectroscopy are performed to investigate the detailed surface reactions of Ru and Cu that facilitate material removal and control corrosion during the CMP of these metals.

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Section: Corrosion Characteristics and Surface Reactions Ofmentioning

confidence: 83%

Investigation of Percarbonate Based Slurry Chemistry for Controlling Galvanic Corrosion during CMP of Ruthenium

Türk¹,

Rock²,

Amanapu

et al. 2013

ECS J. Solid State Sci. Technol.

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“…15 It has also been shown that the carbonate/bicarbonate anions (contained in SPC) can serve as efficient surface modifiers of Cu and Ta to facilitate low pressure CMP of these metals. 16 Guanidine is broadly recognized for its surface complexing function in the contexts of Ru and Ta CMP. 4,17 The carbonate salt of guanidine is chosen here to match the anion component of the other complexing agent, SPC, used in the experimental slurry.…”

mentioning

confidence: 99%

Tribo-Electrochemical Characterization of Ru, Ta and Cu CMP Systems Using Percarbonate Based Solutions

Shi

Simpson

Roy

2015

ECS J. Solid State Sci. Technol.

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Defect-control is a critical requirement for chemical mechanical planarization (CMP) of the ultrathin diffusion barriers considered for the new Cu-interconnects. The challenging task of developing advanced CMP slurries for such systems can be aided by electrochemical evaluations of model CMP schemes under tribological conditions. The present work uses this strategy to characterize an alkaline slurry formulation aimed at minimizing galvanic corrosion in the CMP systems involving Ru, Ta (barrier metals) and Cu (wiring metal). This slurry is based on percarbonate and guanidine additives, and the test metals are polycrystalline disc samples. A particular goal of this study is to explore the essential analytical aspects of evaluating CMP systems in the triboelectrochemical approach. The CMP specific surface reactions are characterized by potentiodynamic polarization and open circuit voltage measurements, performed both in the presence and in the absence of polishing, and by employing abrasive free as well as abrasive (colloidal SiO 2 ) added solutions. The findings of these experiments are further checked by using impedance spectroscopy. The electrochemical mixed potential steps of the CMP promoting reactions are analyzed, and the removable surface species formed by these reactions are discussed. The recent developments in the manufacturing of advanced interconnects have largely centered on the Cu/low-k technology, where the processing challenges are coupled with those of material selection. The introduction of mechanically fragile low-k dielectrics has set strict limits on the usable down-pressure of chemical mechanical planarization (CMP) used in the processing of Cu interconnects. This in turn has driven the strategies for material removal more toward the chemical considerations of CMP, and less reliant on mechanical abrasion.2,3 At the same time, the CMP chemistries of the relatively unconventional new barrier materials have presented other challenges, because in the slurry environment, they often have appeared chemically too inert 4 or too corrosive.5 If the CMP chemistries for these new materials are not properly controlled, the processed wafer can develop surface defects due to erosion and galvanic corrosion activated by the wet CMP process. Such defects are detrimental to device performance, and this issue is particularly relevant for the CMP of ultrathin (< 5 nm) barrier films, where defect-control is often more critical than achieving high rates of material removal. Due to these reasons, the tasks of designing the slurry chemistries for metal CMP have become progressively more complex during recent years. This specific aspect of CMP consumable challenges can be addressed to a large extent by employing laboratory scale evaluations of slurry compositions with electrochemical measurements. The present work is based on this approach.The role of electrochemical reactions (and hence the applicability of electro-analytical tests in this context) is integrated in the overall mechanism of chemically promoted metal-C...

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“…The electrolytes, pHadjusted using HNO 3 , were prepared with reagent grade chemicals (Sigma Aldrich) and triply distilled water. Potentiodynamic and FT-EIS measurements were performed in a three-electrode glass cell of w100 ml volume, outfitted with a Pt counter electrode and a saturated calomel electrode (SCE) reference [25,26]. OCP transients were also recorded using this setup with the counter electrode disconnected.…”

Section: Methodsmentioning

confidence: 99%

“…If the electrode contains spatially discontinuous oxide films, such currents may not show a clear signature of surface passivation under moderate anodic activation. The surface oxides of Ta [25,26,30] and Al [46] formed here in the presence of the NO 3 À /AH À anions are in this category due to the known effects of anion-incorporation under such conditions [47]. Based on these considerations, the anodic component of i corr shown in Fig.…”

Section: Surface Modifying Roles Of Ascorbic Acid On Ta Co and Almentioning

confidence: 98%

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Minimizing the effects of galvanic corrosion during chemical mechanical planarization of aluminum in moderately acidic slurry solutions

Shi

Rock

Türk

et al. 2012

Materials Chemistry and Physics

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Electrochemical investigation of the roles of oxyanions in chemical–mechanical planarization of tantalum and tantalum nitride

Cited by 12 publications

References 47 publications

Investigation of Percarbonate Based Slurry Chemistry for Controlling Galvanic Corrosion during CMP of Ruthenium

Investigation of Percarbonate Based Slurry Chemistry for Controlling Galvanic Corrosion during CMP of Ruthenium

Tribo-Electrochemical Characterization of Ru, Ta and Cu CMP Systems Using Percarbonate Based Solutions

Minimizing the effects of galvanic corrosion during chemical mechanical planarization of aluminum in moderately acidic slurry solutions

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