The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric a...The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric acid(HEDP),and tribasic ammonium citrate(TAC)were investigated by electrochemical techniques,X-ray photoelectron spectrometer(XPS)analysis,nano-scratch tests,AFM measurements,and polishing of Cu-coated blanket wafers.The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions,especially at pH=8.The optimal electrolyte compositions(mass fraction)are 6% HEDP,0.3% TTA and 3% TAC at pH=8.The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential.The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion.The surface topography evolution before and after electrochemical polishing(ECP)illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution,that is,the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate.This understanding is beneficial for optimization of ECMP processes.展开更多
The current-voltage (I-V) curves, such as linear sweep voltammetry (LSV) and cyclic voltammetry (CV), were employed to evaluate the effect of electrolyte concentration on the electrochemical reaction trend. From the I...The current-voltage (I-V) curves, such as linear sweep voltammetry (LSV) and cyclic voltammetry (CV), were employed to evaluate the effect of electrolyte concentration on the electrochemical reaction trend. From the I-V curve, the electrochemical states of active, passive, transient and trans-passive region could be characterized. And then, the mechanism of the process of voltage-induced material removal in electrochemical mechanical polishing (ECMP) of copper was investigated. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses were used to observe the surface profile. Finally, the oxidation and reduction processes of the Cu surface were monitored by the repetition of anodic and cathodic potential from cyclic voltammetry (CV) method in acid-and alkali-based electrolyte.展开更多
Electrochemical behavior of chemical mechanical polishing of copper with oxide passive film was studied by electrochemical measurement technologies. Dependences of polarization curves and electrochemical parameters, t...Electrochemical behavior of chemical mechanical polishing of copper with oxide passive film was studied by electrochemical measurement technologies. Dependences of polarization curves and electrochemical parameters, the rate of formation or removal of passive film of copper on film modifier KClO 3 were investigated. The rules of dependences of corrosion potentials and corrosion current densities on polishing pressure and rotation rate were obtained. It is discovered that the rates of formation and removal of passive film of copper are enhanced, while the polishing pressure and rotation rate are reduced. The experiments show that the CMP processes decrease Tafel slope, increase electron transfer coefficient of anode reaction and decrease the activation energy of corrosion reaction of copper, thereby the corrosion processes are accelerated. The results indicate that CMP slurry recipe, which is composed of NaAc NaOH medium, using KClO 3 as passive film modifier and nano sized γ Al 2O 3 as abrasive, is feasible and reasonable. The technological conditions are 100 r/min, 16 kPa.展开更多
Metal Ti and its alloys have been widely utilized in the fields of aviation, medical science, and micro-electromechanical systems, for its excellent specific strength, resistance to corrosion, and biological compatibi...Metal Ti and its alloys have been widely utilized in the fields of aviation, medical science, and micro-electromechanical systems, for its excellent specific strength, resistance to corrosion, and biological compatibility. As the application of Ti moves to the micro or nano scale, however, traditional methods of planarization have shown their short slabs.Thus, we introduce the method of chemical mechanical polishing（CMP） to provide a new way for the nano-scale planarization method of Ti alloys. We obtain a mirror-like surface, whose flatness is of nano-scale, via the CMP method. We test the basic mechanical behavior of Ti–6Al–4V（Ti64） in the CMP process, and optimize the composition of CMP slurry.Furthermore, the possible reactions that may take place in the CMP process have been studied by electrochemical methods combined with x-ray photoelectron spectroscopy（XPS）. An equivalent circuit has been built to interpret the dynamic of oxidation. Finally, a model has been established to explain the synergy of chemical and mechanical effects in the CMP of Ti–6Al–4V.展开更多
The electrochemical behavior of silicon wafer in alkaline slurry with nano-sized CeO2 abrasive was investigated.The variations of corrosion potential(φcorr)and corrosion current density(Jcorr)of the P-type(100)silico...The electrochemical behavior of silicon wafer in alkaline slurry with nano-sized CeO2 abrasive was investigated.The variations of corrosion potential(φcorr)and corrosion current density(Jcorr)of the P-type(100)silicon wafer with the slurry pH value and the concentration of abrasive CeO2 were studied by polarization curve technologies.The dependence of the polishing rate on the pH and the concentration of CeO2 in slurries during chemical mechanical polishing(CMP)were also studied.It is discovered that there is a large change of φcorr and Jcorr when slurry pH is altered and the Jcorr reaches the maximum(1.306 μA/cm2)at pH 10.5 when the material removal rate(MRR)comes to the fastest value.The Jcorr increases gradually from 0.994 μA/cm2 with 1% CeO2 to 1.304 μA/cm2 with 3% CeO2 and reaches a plateau with the further increase of CeO2 concentration.There is a considerable MRR in the slurry with 3% CeO2 at pH 10.5.The coherence between Jcorr and MRR elucidates that the research on the electrochemical behavior of silicon wafers in the alkaline slurry could offer theoretic guidance on silicon polishing rate and ensure to adjust optimal components of slurry.展开更多
Electrochemical mechanical polishing(ECMP)is a new and highly promising technology.A specific challenge for integrating Ru as barrier in Cu interconnect structures is the galvanic corrosion of Cu that occurs during EC...Electrochemical mechanical polishing(ECMP)is a new and highly promising technology.A specific challenge for integrating Ru as barrier in Cu interconnect structures is the galvanic corrosion of Cu that occurs during ECMP.To mitigate the problem,the benzotriazole(BTA)and ascorbic acid(AA)were chosen as selective anodic and cathodic inhibitors for Cu and Ru,respectively.The optimization of electrolytes at different pHs including BTA,hydroxyethylidenediphosphoric acid(HEDP),and AA were investigated using electrochemical methods.The Ru/Cu removal rate and the planarization efficiency during Ru/Cu ECMP can be approximated using electrochemical measurements of the removal rate,with and without surface abrasion.Chemical systems that exhibit a 1:1 selectivity between the barrier layer and copper would be ideal for the barrier removal step of ECMP.Optimized slurry consists of 20.0 wt%HEDP,0.5 wt%BTA,and 0.3 wt%AA at pH 2.2.Using the optimized slurry,the selectivity of Ru to Cu is near 1.Electrochemical measurements of open circuit potentials,potentiodynamic polarization,and impedance spectroscopy were performed to investigate the galvanic corrosion between ruthenium and copper.展开更多
基金Project(50975058)supported by the National Science Foundation of China
文摘The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric acid(HEDP),and tribasic ammonium citrate(TAC)were investigated by electrochemical techniques,X-ray photoelectron spectrometer(XPS)analysis,nano-scratch tests,AFM measurements,and polishing of Cu-coated blanket wafers.The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions,especially at pH=8.The optimal electrolyte compositions(mass fraction)are 6% HEDP,0.3% TTA and 3% TAC at pH=8.The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential.The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion.The surface topography evolution before and after electrochemical polishing(ECP)illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution,that is,the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate.This understanding is beneficial for optimization of ECMP processes.
基金supported by grant No.R01-2006-000-11275-0 (2008) from the Basic Research Program of the Korea Science & Engineering Foundation
文摘The current-voltage (I-V) curves, such as linear sweep voltammetry (LSV) and cyclic voltammetry (CV), were employed to evaluate the effect of electrolyte concentration on the electrochemical reaction trend. From the I-V curve, the electrochemical states of active, passive, transient and trans-passive region could be characterized. And then, the mechanism of the process of voltage-induced material removal in electrochemical mechanical polishing (ECMP) of copper was investigated. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses were used to observe the surface profile. Finally, the oxidation and reduction processes of the Cu surface were monitored by the repetition of anodic and cathodic potential from cyclic voltammetry (CV) method in acid-and alkali-based electrolyte.
文摘Electrochemical behavior of chemical mechanical polishing of copper with oxide passive film was studied by electrochemical measurement technologies. Dependences of polarization curves and electrochemical parameters, the rate of formation or removal of passive film of copper on film modifier KClO 3 were investigated. The rules of dependences of corrosion potentials and corrosion current densities on polishing pressure and rotation rate were obtained. It is discovered that the rates of formation and removal of passive film of copper are enhanced, while the polishing pressure and rotation rate are reduced. The experiments show that the CMP processes decrease Tafel slope, increase electron transfer coefficient of anode reaction and decrease the activation energy of corrosion reaction of copper, thereby the corrosion processes are accelerated. The results indicate that CMP slurry recipe, which is composed of NaAc NaOH medium, using KClO 3 as passive film modifier and nano sized γ Al 2O 3 as abrasive, is feasible and reasonable. The technological conditions are 100 r/min, 16 kPa.
基金Project supported by the National Major Scientific and Technological Special Project during the Twelfth Five-year Plan Period of China(Grant No.2009ZX02030-1)the National Natural Science Foundation of China(Grant No.51205387)+1 种基金the Support by Science and Technology Commission of Shanghai City,China(Grant No.11nm0500300)the Science and Technology Commission of Shanghai City,China(Grant No.14XD1425300)
文摘Metal Ti and its alloys have been widely utilized in the fields of aviation, medical science, and micro-electromechanical systems, for its excellent specific strength, resistance to corrosion, and biological compatibility. As the application of Ti moves to the micro or nano scale, however, traditional methods of planarization have shown their short slabs.Thus, we introduce the method of chemical mechanical polishing（CMP） to provide a new way for the nano-scale planarization method of Ti alloys. We obtain a mirror-like surface, whose flatness is of nano-scale, via the CMP method. We test the basic mechanical behavior of Ti–6Al–4V（Ti64） in the CMP process, and optimize the composition of CMP slurry.Furthermore, the possible reactions that may take place in the CMP process have been studied by electrochemical methods combined with x-ray photoelectron spectroscopy（XPS）. An equivalent circuit has been built to interpret the dynamic of oxidation. Finally, a model has been established to explain the synergy of chemical and mechanical effects in the CMP of Ti–6Al–4V.
基金Project(2005DFBA028)supported by the International Cooperation of Science and Technology Ministry of ChinaProject(LA07023)supported by the National Undergraduate Innovative Experiment Plan
文摘The electrochemical behavior of silicon wafer in alkaline slurry with nano-sized CeO2 abrasive was investigated.The variations of corrosion potential(φcorr)and corrosion current density(Jcorr)of the P-type(100)silicon wafer with the slurry pH value and the concentration of abrasive CeO2 were studied by polarization curve technologies.The dependence of the polishing rate on the pH and the concentration of CeO2 in slurries during chemical mechanical polishing(CMP)were also studied.It is discovered that there is a large change of φcorr and Jcorr when slurry pH is altered and the Jcorr reaches the maximum(1.306 μA/cm2)at pH 10.5 when the material removal rate(MRR)comes to the fastest value.The Jcorr increases gradually from 0.994 μA/cm2 with 1% CeO2 to 1.304 μA/cm2 with 3% CeO2 and reaches a plateau with the further increase of CeO2 concentration.There is a considerable MRR in the slurry with 3% CeO2 at pH 10.5.The coherence between Jcorr and MRR elucidates that the research on the electrochemical behavior of silicon wafers in the alkaline slurry could offer theoretic guidance on silicon polishing rate and ensure to adjust optimal components of slurry.
基金the National Natural Science Foundation of China(No.50975058)。
文摘Electrochemical mechanical polishing(ECMP)is a new and highly promising technology.A specific challenge for integrating Ru as barrier in Cu interconnect structures is the galvanic corrosion of Cu that occurs during ECMP.To mitigate the problem,the benzotriazole(BTA)and ascorbic acid(AA)were chosen as selective anodic and cathodic inhibitors for Cu and Ru,respectively.The optimization of electrolytes at different pHs including BTA,hydroxyethylidenediphosphoric acid(HEDP),and AA were investigated using electrochemical methods.The Ru/Cu removal rate and the planarization efficiency during Ru/Cu ECMP can be approximated using electrochemical measurements of the removal rate,with and without surface abrasion.Chemical systems that exhibit a 1:1 selectivity between the barrier layer and copper would be ideal for the barrier removal step of ECMP.Optimized slurry consists of 20.0 wt%HEDP,0.5 wt%BTA,and 0.3 wt%AA at pH 2.2.Using the optimized slurry,the selectivity of Ru to Cu is near 1.Electrochemical measurements of open circuit potentials,potentiodynamic polarization,and impedance spectroscopy were performed to investigate the galvanic corrosion between ruthenium and copper.
