A Model of Material Removal and Post Process Surface Topography for Copper CMP

Choi, Seungchoun; Doyle, Fiona M.; Dornfeld, David

doi:10.1016/j.proeng.2011.11.082

Cited by 13 publications

(11 citation statements)

References 11 publications

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“…Material behavior of copper during CMP at nano-scale.-The maximum shear stress induced in copper by indentation of an abrasive during CMP was estimated to be of the order of a few GPa, 27,42 which is similar to the theoretical shear strength of copper. However, friction between abrasive particles and copper reduces the overall threshold for plasticity of copper during CMP.…”

Section: Discussionmentioning

confidence: 72%

“…13,18,25,26 However, its application has not been successful to date to predict the MRR because the indentation load and depth and the size of an indenter were larger than those appropriate for CMP (Figure 4). 27 It is well known that indentation hardness shows a size effect, with larger indenter size or indentation depth yielding lower apparent indentation hardnesses. [28][29][30][31][32][33][34] As the indented volume decreases the probability of crystallographic defects being present under an indenter decreases, leading to enhanced resistance to plastic deformation.…”

Section: Discussionmentioning

confidence: 99%

“…During CMP itself, the probability that a given location on a wafer is contacted by abrasive particles held under a pad asperity during interaction between the asperity and the wafer is defined as the removal efficiency. 27,68 The removal efficiency during CMP has been determined to be smaller than unity, meaning that a given point on a wafer during CMP is contacted less than once on average during the contact between a pad asperity and a wafer. 27,68 It follows, then, that the period during which a given location on the surface of copper is exposed to the slurry between successive contacts with abrasive particles is of the same order as the time interval between consecutive asperity and wafer interactions, about 1 ms with typical commercial pads and CMP operating parameters.…”

Section: Relationship Between Hardness Of Copper and Mrr Duringmentioning

confidence: 99%

“…27,68 The removal efficiency during CMP has been determined to be smaller than unity, meaning that a given point on a wafer during CMP is contacted less than once on average during the contact between a pad asperity and a wafer. 27,68 It follows, then, that the period during which a given location on the surface of copper is exposed to the slurry between successive contacts with abrasive particles is of the same order as the time interval between consecutive asperity and wafer interactions, about 1 ms with typical commercial pads and CMP operating parameters. The next interaction with an abrasive particle would, of course, remove at least part of this surface material, and expose new copper surface material that had not hitherto been exposed to the slurry chemicals.…”

Section: Relationship Between Hardness Of Copper and Mrr Duringmentioning

confidence: 99%

See 3 more Smart Citations

Material Removal Mechanism during Copper Chemical Mechanical Planarization Based on Nano-Scale Material Behavior

Choi

Doyle

Dornfeld

2017

ECS J. Solid State Sci. Technol.

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Comparison of the experimentally measured electrochemical corrosion rate and the physical material removal rate (MRR) revealed that during copper chemical mechanical planarization (CMP) most of the copper was removed mechanically by interaction with sliding abrasive particles. The mechanism for mechanical removal of copper was explained by considering literature values of the properties of copper at the nano-scale. Although the force applied on the copper by abrasive particles may be insufficient to initiate plastic deformation, friction between moving abrasive particles and copper reduces the maximum Hertz pressure required for plasticity. Crystallographic defects and a copper surface roughened by repetitive abrasions and chemical attack further lower the local threshold for plastic deformation, leading to selective plastic deformation of copper at weakened regions. The plastically deformed copper is then removed by a mechanism similar to cutting, releasing free debris that is subsequently dissolved by the oxidizer and/or complexing agent in the CMP slurry. Hardness values obtained from AFM tip scratching experiments on chemically treated copper predicted the MRR behavior during CMP well. In contrast, hardness values obtained by nanoindentation, where the applied force and the tip diameter were much larger than those during AFM tip scratching, yielded poor predictions of the MRR.

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Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Section: Relationship Between Hardness Of Copper and Mrr Duringmentioning

confidence: 99%

Section: Relationship Between Hardness Of Copper and Mrr Duringmentioning

confidence: 99%

See 2 more Smart Citations

Material Removal Mechanism during Copper Chemical Mechanical Planarization Based on Nano-Scale Material Behavior

Choi

Doyle

Dornfeld

2017

ECS J. Solid State Sci. Technol.

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“…t as−as = πd as 4vr contact [4] where r contact is an increasing function of the down pressure 6,7 and d as can either increase or stay constant with the down pressure. Both can be experimentally characterized using confocal reflectance interference contrast microscopy (C-RICM) 6 or dual emission laser induced fluorescence (DELIF).…”

Section: Discussionmentioning

confidence: 99%

Editors' Choice—Efficiency of a CMP Pad at Removing Protective Material from Copper during CMP

Choi

Doyle

Dornfeld

2017

ECS J. Solid State Sci. Technol.

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The efficiency of a pad asperity and abrasives embedded between the asperity and wafer at removing the protective material on the surface of copper (removal efficiency) during chemical mechanical planarization (CMP) was determined experimentally using current densities from in situ electrochemical measurements while polishing with a slurry containing BTA. The removal efficiency was insentitive to the pressure and sliding velocity, but was dictated by the pad surface topography parameters and abrasive concentration in the slurry. An analytical estimate was derived by comparing the trajectories of a pad asperity and the abrasives embedded in the asperity. Comparison of the experimental and analytical estimate suggests that the asperities are deformed enough by the embedded abrasives to contact the surface of copper at abrasive concentrations up to 1 wt%. At higher concentrations up to 5 wt%, the asperities deflected to a lesser amount, making the force exerted on the copper increase. At these higher concentrations, some of the copper interacting with the squeezed abrasives was plastically deformed, yielding higher removal efficiency than when elastically deformed. The removal efficiency can be used as a standard metric for assessing the material removal ability of various consumables such as slurry, CMP pad and pad conditioner.

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Efficient Chemical Mechanical Polishing of AISI 52100 Bearing Steel with TiSol-NH4 Dispersion-Based Slurries

Jiang

Liu

et al. 2020

Tribol Lett

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A Model of Material Removal and Post Process Surface Topography for Copper CMP

Cited by 13 publications

References 11 publications

Material Removal Mechanism during Copper Chemical Mechanical Planarization Based on Nano-Scale Material Behavior

Material Removal Mechanism during Copper Chemical Mechanical Planarization Based on Nano-Scale Material Behavior

Editors' Choice—Efficiency of a CMP Pad at Removing Protective Material from Copper during CMP

Efficient Chemical Mechanical Polishing of AISI 52100 Bearing Steel with TiSol-NH4 Dispersion-Based Slurries

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