An Evaluation of the Effects of Benzotriazole in NH4OH Slurry for Copper CMP

ABSTRACTChemical mechanical polishing (CMP) of copper using alumina-based NH4OH slurry containing benzotriazole (BTA) has been evaluated in terms of polish efficiency and viability. Dishing of damascene copper patterns can result from a combination of chemical dissolution and mechanical abrasion due to the deformed polishing pad bending into the recessed copper regions. The addition of at least 0.1 wt.% BTA to the slurry leads to the formation of a thin Cu(I)-BTA polymer on the copper surface during CMP. This polymer reduces the amount of dishing by an order of magnitude. At the same time, however, the CMP polish rate falls sharply with the addition of 0.1 - 0.25 wt.% BTA to the slurry. Above 0.25 wt.% BTA, the polish rate falls no further. Stability of alumina particles in the NH4OH slurry is found to deteriorate with the addition of BTA. Integrated copper/barrier electromigration resistance test structures with large contact areas (2×2mm) have been successfully patterned using a 2-step CMP/etching process scheme, using a BTA-containing slurry to minimise dishing.

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Synergy between chemical dissolution and mechanical abrasion during chemical mechanical polishing of copper

10.31274/rtd-180813-8735 ◽

2005 ◽

Author(s):

Wei Che

Keyword(s):

Chemical Mechanical Polishing ◽

Mechanical Polishing ◽

Chemical Dissolution ◽

Mechanical Abrasion

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Atomistic Mechanisms Underlying Chemical Mechanical Planarization of Copper

MRS Proceedings ◽

10.1557/proc-767-f1.8 ◽

2003 ◽

Vol 767 ◽

Author(s):

Y.Y. Ye ◽

R. Biswas ◽

A. Bastawros ◽

A. Chandra

Keyword(s):

Chemical Mechanical Planarization ◽

Abrasive Particle ◽

Copper Surface ◽

Copper Interconnects ◽

Embedded Atom Method ◽

Chemical Dissolution ◽

Copper Surfaces ◽

Mechanical Abrasion ◽

Embedded Atom ◽

Frictional Forces

AbstractWith an aim to understanding the fundamental mechanisms underlying chemical mechanical planarization (CMP) of copper, we simulate the nanoscale polishing of a copper surface with molecular dynamics utilizing the embedded atom method. Mechanical abrasion produces rough planarized surfaces with a large chip in front of the abrasive particle, and dislocations in the bulk of the crystal. The addition of chemical dissolution leads to very smooth planarized copper surfaces and considerably smaller frictional forces that prevent the formation of bulk dislocations. This is a first step towards understanding the interplay between mechanistic material abrasion and chemical dissolution in chemical mechanical planarization of copper interconnects.

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Investigations of the interaction between different barrier metals and copper surface during the chemical-mechanical polishing

10.1109/mam.1997.621087 ◽

1997 ◽

Author(s):

Z. Zeidler ◽

Z. Stavreva ◽

M. Plotner ◽

K. Drescher

Keyword(s):

Chemical Mechanical Polishing ◽

Copper Surface ◽

Mechanical Polishing

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Effect of Corrosion Inhibitor (BTA) in Citric Acid based Slurry on Cu CMP

MRS Proceedings ◽

10.1557/proc-867-w1.3 ◽

2005 ◽

Vol 867 ◽

Author(s):

In-Kwon Kim ◽

Young-Jae Kang ◽

Yi-Koan Hong ◽

Jin-Goo Park

Keyword(s):

Etch Rate ◽

Removal Rate ◽

Passivation Layer ◽

Chemical Dissolution ◽

H2o2 Concentration ◽

Removal Rates ◽

Abrasive Particles ◽

Mechanical Abrasion ◽

Abrasion Rate ◽

Cu Cmp

AbstractIn this study, the effect of BTA on polishing behavior was investigated as functions of H2O2, slurry pH and abrasive particles. The addition of BTA effectively prevented Cu from etching by forming the passivation layer of Cu-BTA regardless of pH and H2O2 concentration in slurry. A thinner passivation layer was grown on Cu in BTA added slurry solutions with a higher contact angle of 60°. The dynamic etch rate, the removal rate with abrasive free slurry, also decreased when BTA was added in slurry at pH 2, 4 and 6. The removal rate of Cu was strongly dependent on types of abrasive particles in slurry. The larger hardness of slurry abrasive particles, the higher removal rates of Cu. The reduction of removal rates in BTA added slurry was determined by the competition between chemical dissolution rate and mechanical abrasion rate.

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Transient Electrochemical Measurements During Copper Chemical Mechanical Polishing

MRS Proceedings ◽

10.1557/proc-767-f2.9 ◽

2003 ◽

Vol 767 ◽

Cited By ~ 1

Author(s):

Seung-Mahn Lee ◽

Wonseop Choi ◽

Valentin Craciun ◽

Rajiv K. Singh

Keyword(s):

Surface Layer ◽

Reaction Kinetics ◽

Chemical Mechanical Polishing ◽

Copper Surface ◽

Mechanical Polishing ◽

Electrochemical Measurements ◽

Chemically Modified ◽

Modified Surface ◽

Selection Of ◽

Modified Surface Layer

AbstractChronoamperometry was used to investigate the reaction/passivation kinetics and thickness of the chemically modified surface layer on the copper during chemical mechanical polishing (CMP). The result showed that the reaction/passivation kinetics and the thickness of the chemically modified surface layer are strongly dependent on the chemistry of CMP slurry in the chemical aspect of CMP and play critical keys in the selection of the chemistry and its concentration. BTA and H2O2 enhanced the passivation kinetics, resulting in thinner layer on the copper surface. In addition, the reaction kinetics increased as pH decreased.

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Modified Preston Equation- Revisited

MRS Proceedings ◽

10.1557/proc-566-149 ◽

1999 ◽

Vol 566 ◽

Cited By ~ 1

Author(s):

S Ramarajan ◽

S.V. Babu

Keyword(s):

Empirical Model ◽

The Other ◽

Ferric Nitrate ◽

Rate Data ◽

Velocity Dependence ◽

Effect Of Pressure ◽

Reactive Chemicals ◽

Alumina Particles ◽

Polish Rate

The effect of pressure and velocity on the polish rates of copper was determined in DI water and in the presence of ferric nitrate, H202/glycine, and NH4OH with alumina particles as the abrasives. The polish rate shows a stronger dependence on velocity than that predicted by the Preston equation in the case of ferric nitrate, a highly reactive chemical. The velocity dependence is weaker for the other two less reactive chemicals, and is the same as that predicted by Preston equation for DI water. Our earlier empirical model, R = KPV + BV + Rc, where K, B, and Rc are constants, describes all the polish rate data satisfactorily.

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Use of Malonic Acid in Chemical-Mechanical Polishing ( CMP ) of Tungsten

MRS Proceedings ◽

10.1557/proc-477-115 ◽

1997 ◽

Vol 477 ◽

Cited By ~ 1

Author(s):

L. Zhang ◽

S. Raghavan

Keyword(s):

Zeta Potential ◽

Malonic Acid ◽

Chemical Mechanical Polishing ◽

Mechanical Polishing ◽

Small Scale ◽

Ph Values ◽

Particulate Contamination ◽

Principal Objective ◽

Alumina Particles ◽

Negative Zeta Potential

ABSTRACTThe use of malonic acid as an additive in alumina slurries used for the chemical mechanical polishing ( CMP ) of tungsten has been explored for the reduction of particulate contamination. The principal objective of this work was to delineate conditions under which alumina contamination on polished surfaces could be reduced.The interaction between malonic acid and alumina particles has been investigated through electrokinetic and adsorption measurements. At suitable malonic acid concentrations and pH values, tungsten and alumina surfaces develop a negative zeta potential resulting in conditions conducive to reduced particulate contamination. Small scale polishing experiments have been carried out to relate electrokinetic results to the level of particulate contamination after polishing.

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Investigations of the interaction between different barrier metals and copper surface during the chemical-mechanical polishing

10.1109/mam.1998.887542 ◽

1998 ◽

Author(s):

D. Zeidler ◽

Z. Stavreva ◽

M. Plotner ◽

K. Drescher

Keyword(s):

Chemical Mechanical Polishing ◽

Copper Surface ◽

Mechanical Polishing

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Synergy between Chemical Dissolution and Mechanical Abrasion during Chemical Mechanical Polishing of Copper

MRS Proceedings ◽

10.1557/proc-867-w5.8 ◽

2005 ◽

Vol 867 ◽

Cited By ~ 2

Author(s):

Wei Che ◽

Ashraf Bastawros ◽

Abhijit Chandra

Keyword(s):

Residual Stress ◽

Chemical Etching ◽

Material Removal ◽

Wear Test ◽

Wear Depth ◽

Chemical Dissolution ◽

Removal Mechanism ◽

Material Removal Mechanism ◽

Soft Layer ◽

Mechanical Abrasion

AbstractThe synergistic roles of chemical dissolution and mechanical abrasion on the material removal mechanism during CMP process are explored. A set of nano-wear experiments are conducted on electro-plated copper surfaces with systematic exposure to active slurries. Initial results of in situ wear test in chemically active slurry showed an increased material removal rate (MRR) relative to a dry wear test. To understand the synergistic effects of chemical dissolution and mechanical abrasion, we have investigated two plausible mechanisms of material removal. Mechanism-I is based on chemical dissolution enhanced mechanical abrasion. A soft layer of chemical products is assumed to be formed on top of the polished surface due to chemical reaction with a rate much faster than the mechanical abrasion rate. It is then followed by a gentle mechanical abrasion of that soft layer. An increase in the MRR of up to 100% is identified based on the etching time and the down force. Mechanism-II is based on mechanical abrasion accelerated chemical etching. In this case, the nano-wear experiments are first performed to generate local variation of the residual stress levels, and then followed by chemical etching to investigate the variation of the wear depth and the evolution of surface topography due to etching. It is found that the residual stress caused by the mechanical wear enhances the chemical etching rate, as manifested by the increase of wear depth. The developed understanding from these experiments can be used in future studies to control the rates of chemical dissolution and mechanical abrasion as well as investigating the various process-induced defects.

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