Electrochemical Studies of Copper Chemical Mechanical Polishing Mechanism: Effects of Oxidizer Concentration

2003 ◽  
Vol 767 ◽  
Author(s):  
J. Lu ◽  
J.E. Garland ◽  
C.M. Petite ◽  
S.V. Babu ◽  
D. Roy
Keyword(s):  
Electrochemical Impedance ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Electrochemical Techniques ◽  
Copper Surface ◽  
Ex Situ ◽  
Surface Films ◽  
Copper Disk ◽  
Dissolution Tests ◽  
Oxidizer Concentration

AbstractThe process of copper chemical-mechanical planarization (CMP) can be considered as an erosion corrosion process. Such a process can be efficiently studied by in situ and ex situ electrochemical techniques, such as potentiodynamic scan and electrochemical impedance spectroscopy (EIS). Using a copper disk as the working electrode in an electrochemical cell, slurries with different oxidizer concentrations have been investigated with the aforementioned techniques. Corresponding dissolution tests were also studied and compared. It is shown that changing the oxidizer concentration leads to the formation of surface films with different structure and composition on the copper surface during CMP process. The nature of these films controls the rate of copper corrosion. These results could be used to explain the change of copper removal rate in different oxidizer concentration, as well as to understand the copper CMP mechanism.

scholarly journals Urea as a complexing agent for selective removal of Ta and Cu in sodium carbonate based alumina CMP slurry

2021 ◽  
pp. 49-49
Author(s):  
Arpita Shukla ◽  
Victoria Selvam ◽  
Manivannan Ramachandran
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Sodium Carbonate ◽  
Corrosion Potential ◽  
Electrochemical Impedance ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Corrosion Current ◽  
Complexing Agent ◽  
Downward Pressure

This work reports urea as a promising complexing agent in sodium carbonate (Na2CO3) based alumina slurry for chemical mechanical planarization (CMP) of tantalum (Ta) and copper (Cu). Ta and Cu were polished using Na2CO3 (1 wt.%) with alumina (2 wt.%) in the presence and absence of urea. The effect of slurry pH, urea concentration, applied downward pressure and platen rotational speed were deliberated and the outcomes were conveyed. Prior to the addition of urea, Ta removal rate (RR) was observed to enhance with pH from acidic to alkaline having maximum RR at pH 11. However, Cu RR decreases with increasing pH with minimum RR at pH 11. With the addition of urea in the slurry, Cu to Ta removal rate selectivity of nearly 1:1 is encountered at pH 11. The addition of urea boosts the Ta RR and suppresses Cu RR at the same time at 11 pH, as it adsorbs on the metal surface. Potentiodynamic polarization was conducted to determine the corrosion current (Icorr) and the corrosion potential (Ecorr). The electrochemical impedance spectroscopy (EIS) of both the metals was carried out in the proposed formulation and the obtained outcomes were elaborated.

Corrosion Inhibiting Effect on Copper Chemical Mechanical Planarization (CMP) in Fe(NO3)3 Based Slurries

2005 ◽  
Vol 291-292 ◽  
pp. 395-400
Author(s):  
Dong Ming Guo ◽  
X.J. Li ◽  
Zhu Ji Jin ◽  
Ren Ke Kang
Keyword(s):  
Surface Roughness ◽  
Large Scale ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Etching Rate ◽  
Copper Surface ◽  
Force Microscopy ◽  
Composition Modification ◽  
Planarization Process ◽  
Analysis System

The slurry of Copper chemical mechanical planarization for ultra large-scale integrate circuit (ULSI) usually contains oxidizer, etchant, complexing reagent and corrosive inhibitor. In planarization process, the corrosive inhibitor has an important effect on the planarization. Only if the concave surface of the wafer is properly protected from corrosion by the inhibitor, the process can obtain perfect surface planarity. In this paper, with Fe(NO3)3 as an oxidant and several corrosive inhibitors selected, the corrosive efficiency of slurries are investigated. The static etching rate and the polishing material removal rate of wafer are obtained. The electrochemical behavior of the slurry is investigated by the potentiodynamic polarization studies. And the inhibitive efficiency of the related corrosive inhibitors is calculated from the polarization data. X-ray diffraction is applied to analyze the composition modification of the copper surface. Atom force microscopy is applied to measure the surface topography of corrosive copper wafer and the value of surface roughness is measured by ZYGO surface analysis system. The result shows that the benzotriazole (BTA) is a perfect corrosive inhibitor. With addition of 0.1wt% BTA into 1.5wt% Fe(NO3)3 solution, the inhibitive efficiency can reach 99.1%. The polishing test shows that if only 1.5wt% Fe(NO3)3 is added as an oxidizer without any other additive, the surface roughness of the polished wafer is 26.9Å, while with 0.1wt%BTA added in the meantime, 5.2 Å of surface roughness can be obtained.

Selectivity Studies On Tantalum Barrier Layer In Copper CMP

2003 ◽  
Vol 767 ◽  
Author(s):  
Arun Vijayakumar ◽  
Tianbao Du ◽  
Kalpathy B. Sundaram ◽  
Vimal Desai
Keyword(s):  
Barrier Layer ◽  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Electrochemical Techniques ◽  
Copper Metallization ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Analysis Techniques ◽  
Diffusion Barrier Layer

AbstractCopper metallization in sub-0.18 μm semiconductor devices is achieved by combining the dual damascence techniques followed by chemical mechanical planarization (CMP). Tantalum and its nitride have been identified as the diffusion barrier layer for copper metallization. However, the wide differences in properties between copper and tantalum layers result in selectivity problems during CMP process. The aim of this work is to obtain a better understanding on the slurry selectivity for copper and tantalum and to develop slurries with best selectivity performance. In this work, the effect of several chemical parameters (abrasive type, oxidizer type, concentration, pH etc.) was studied through static and dynamic tests using advanced electrochemical techniques and surface analysis techniques. The surface layers of the statically etched copper and tantalum discs were investigated using X-ray photoelectron spectroscopy (XPS) and surface planarity was studied using atomic force microscopy (AFM). Polishing rates results show that alumina-based slurry polished copper very well whereas tantalum removal rate was low. However, for the silica-based slurry the tantalum shows much higher removal rate than copper and better surface planarity was obtained.

The pH Effect On Chemical Mechanical Planarization Of Copper

2003 ◽  
Vol 767 ◽  
Author(s):  
Tianbao Du ◽  
Vimal Desai
Keyword(s):  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Ph Effect ◽  
Chemical Mechanical Planarization ◽  
Electrochemical Techniques ◽  
Surface Layers ◽  
Removal Rates ◽  
Ph Values ◽  
Alkaline Conditions ◽  
Static Conditions

AbstractThis study explores the effect of pH on the chemical mechanical polishing (CMP) characteristics of copper in H2O2 and KIO3 based slurries under various dynamic and static conditions. High purity copper disc was used to study the dissolution and oxidation kinetics at various pH (2 to 10) with 5% H2O2 or 0.1M KIO3. Electrochemical techniques were used to investigate the dissolution/passivation behavior of Cu. The affected surface layers of the statically etched Cu-disc were investigated using X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). In 5% H2O2, the Cu removal rate decreases with an increase in pH and reaches minimum at pH 6, and then increases under alkaline conditions. XPS results indicate that the surface oxide formed at various pH values was responsible for this CMP trend. However, with 0.1M KIO3, the CMP removal rates were found to be lower at pH 2. The maximum was observed at pH 4, then the removal rate decreased with the increase of pH. The lower value of removal rate at pH2 was due to the fast interaction between Cu and KIO3 and the precipitation of CuI on the pad, which makes the pad glassy, resulting in lowered removal rates. This was confirmed by XPS measurements. The decreased CMP removal rates when the pH is higher than 4 might be due to the weaker oxidation power of KIO3 with the increase of pH.

Properties of Oxide Formed on Aluminium in Aqueous Acetate Buffer

2006 ◽  
Vol 519-521 ◽  
pp. 717-722 ◽  
Author(s):  
N. Giskeødegård ◽  
O. Blajiev ◽  
A. Hubin ◽  
H. Terryn ◽  
Ola Hunderi ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Potential Temperature ◽  
Ex Situ ◽  
Pure Aluminium ◽  
Film Properties ◽  
Hydrated Layer ◽  
Transmission Electron ◽  
Controlled Potential

The properties of oxide formed on pure aluminium in acetate buffers under controlled potential, temperature, and pH are characterized by in situ electrochemical techniques and spectroscopic visual ellipsometry (VISSE). Monitoring the current density (cd) during transition between different applied potentials gives direct information about Faradaic changes in the oxide properties, while the ellipsometer monitors the changes in the actual thickness and refractive index of the film. Electrochemical impedance spectroscopy (EIS) reveals, in addition to film properties, information about the charge transfer processes and adsorption at steady-state conditions. VISSE and ex situ transmission electron microscopy (TEM) indicate the presence of a two layered oxide structure, consisting of the barrier and a porous hydrated layer. The thickness and density of these two layers are monitored in situ during growth and dissolution. The thickness of the barrier layer depends reversibly on the applied potential, while the thickness of the hydrated layer is less affected by the potential. The absorption sensitive parameter is correlated with the buffer concentration and therefore believed to be related to the acetate.

The Important Role of Oxidant in Copper Interconnection Chemical Mechanical Polishing for GLSI

2010 ◽  
Vol 663-665 ◽  
pp. 1111-1114 ◽  
Author(s):  
Xiao Yan Liu ◽  
Yu Ling Liu ◽  
Xin Huan Niu ◽  
Zhi Wen Zhao ◽  
Yi Hu
Keyword(s):  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Copper Surface ◽  
Surface Topology ◽  
Passivation Film ◽  
Low Area ◽  
Mechanical Removal ◽  
Copper Interconnection ◽  
High Area

Chemical mechanical planarization (CMP) of copper interconnection in hydrogen peroxide (H2O2) as oxidizer based alkaline slurry was investigated. The new model is put forward, which is based on the characteristic of H2O2, chemical kinetics and mechanical removal. This properties of H2O2 can be effectively compensated the defect of surface topology during the process of polishing. Researcher previous study has shown that the surface is largely copper metal with Cu2O at low H2O2 concentrations and largely CuO at high H2O2 concentrations. Cu2O is more easily removed by both chemical and mechanical processes than CuO. During the CMP process, as the oxidizer concentration increases, the removal rate goes up initially followed by a gradual decay. This characteristic of oxidizer is used to achieve copper surface global planarity. The surface planarity was achieved by removing high area on the surface more quickly relative to the low area, because the concentration of Cu2O in the low area as the passivation film is more than the high area. Meanwhile the passivation film of the low area is thicker than the high area. In order to achieve polishing process optimization, the influence of pH adjustment and pressure, are also taken into consideration. Combining both RR and PE, the optimal H2O2 concentration and pressures are in range 1.0 ~1.5 vol% and 0.04 ~0.07 mpa, respectively. The roughness of surface which is measured by AFM is 0.49 after CMP.

The Application of Chemical Mechanical Polishing for Nickel Used in MEMS Devices

2004 ◽  
Vol 816 ◽  
Author(s):  
Arun Vijayakumar ◽  
Tianbao Du ◽  
Kalpathy B. Sundaram ◽  
Vimal Desai
Keyword(s):  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Electrochemical Techniques ◽  
Device Fabrication ◽  
Complexing Agent ◽  
Nickel Salt ◽  
Mems Devices ◽  
Surface Layers ◽  
Micro Electro Mechanical Systems

AbstractChemical mechanical planarization (CMP) has found extensive application in the fabrication of micro-electro-mechanical systems (MEMS). Nickel and Nickel based alloys are known to possess favorable properties that make them promising candidates to realize movable structures for MEMS applications. The development of CMP slurry chemistry for Ni that provides good CMP performance is the key in enabling CMP technology for Nickel based MEMS device fabrication. Unfortunately, very little work has been reported in terms of the electrochemical interaction of Ni with various CMP slurry constituents such as oxidizers, complexants and inhibitors. In this study, CMP of nickel was performed using H2O2 as oxidizer and alumina particles as abrasives. Electrochemical techniques were used to investigate the dissolution/passivation behavior of high-purity Ni under static and dynamic conditions in slurries at pH 4 with the addition of oxidizer, complexing agent and nickel salt. The affected surface layers of the statically etched Ni-disc were investigated using X-ray photoelectron spectroscopy (XPS). The Ni removal rate increased with the addition of oxidizer and further increased with the addition of complexing agent and nickel salt. The electrochemical results indicate that the surface chemistry and electrochemical characteristic of Ni play an important role in controlling the polishing behavior.

Performance of coatings containing treated silica fume in the corrosion protection of reinforced concrete

2018 ◽  
Vol 47 (4) ◽  
pp. 350-359 ◽  
Author(s):  
Nivin M. Ahmed ◽  
Mostafa G. Mohamed ◽  
Reham H. Tammam ◽  
Mohamed R. Mabrouk
Keyword(s):  
Reinforced Concrete ◽  
Silica Fume ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Dual Function ◽  
Core Shell ◽  
Protection Efficiency ◽  
Content Type ◽  
Anticorrosive Pigments

Purpose This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent silica fume (core) with 10-20 per cent phosphates (shell) previously, to play dual functions simultaneously as anticorrosive pigments in coating formulations and as an anticorrosive admixture in concrete even if it is not present in the concrete itself. Two comparisons were held out to show the results of coatings on rebars containing core-shell pigments in concrete, and concrete admixtured with silica fume can perform a dual function as anticorrosive pigment and concrete admixture. The evaluation of corrosion protection efficiency of coatings containing core-shell pigments and those containing phosphates was performed. Design/methodology/approach Simple chemical techniques were used to prepare core-shell pigments, and their characterization was carried out in a previous work. These pigments were incorporated in solvent-based paint formulations based on epoxy resin. Different electrochemical techniques such as open-circuit potential and electrochemical impedance spectroscopy were used to evaluate the anticorrosive efficiency of the new pigments. Findings The electrochemical measurements showed that concrete containing coated rebars with core-shell pigments exhibited almost similar results to that of concrete admixtured with silica fume. Also, the anticorrosive performance of coatings containing Si-Ph pigments offered protection efficiency almost similar to that of phosphates, proving that these new pigments can perform both roles as anticorrosive pigment and concrete admixture. Originality/value Although the new Si-Ph pigments contain more than 80 per cent waste material, its performance can be compared to original phosphate pigments in the reinforced concrete.

scholarly journals Novel Abrasive-Impregnated Pads and Diamond Plates for the Grinding and Lapping of Single-Crystal Silicon Carbide Wafers

2021 ◽  
Vol 11 (4) ◽  
pp. 1783
Author(s):  
Ming-Yi Tsai ◽  
Kun-Ying Li ◽  
Sun-Yu Ji
Keyword(s):  
Silicon Carbide ◽  
Wear Rate ◽  
Single Crystal ◽  
Traditional Method ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Diamond Grit ◽  
Ceramic Binder

In this study, special ceramic grinding plates impregnated with diamond grit and other abrasives, as well as self-made lapping plates, were used to prepare the surface of single-crystal silicon carbide (SiC) wafers. This novel approach enhanced the process and reduced the final chemical mechanical planarization (CMP) polishing time. Two different grinding plates with pads impregnated with mixed abrasives were prepared: one with self-modified diamond + SiC and a ceramic binder and one with self-modified diamond + SiO2 + Al2O3 + SiC and a ceramic binder. The surface properties and removal rate of the SiC substrate were investigated and a comparison with the traditional method was conducted. The experimental results showed that the material removal rate (MRR) was higher for the SiC substrate with the mixed abrasive lapping plate than for the traditional method. The grinding wear rate could be reduced by 31.6%. The surface roughness of the samples polished using the diamond-impregnated lapping plate was markedly better than that of the samples polished using the copper plate. However, while the surface finish was better and the grinding efficiency was high, the wear rate of the mixed abrasive-impregnated polishing plates was high. This was a clear indication that this novel method was effective and could be used for SiC grinding and lapping.

scholarly journals Corrosion of Steel Rebars in Anoxic Environments. Part I: Electrochemical Measurements

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2491
Author(s):  
Elena Garcia ◽  
Julio Torres ◽  
Nuria Rebolledo ◽  
Raul Arrabal ◽  
Javier Sanchez
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Chloride Content ◽  
Offshore Platforms ◽  
Anoxic Conditions ◽  
Current Limit ◽  
Anoxic Environments ◽  
Corrosion Of Steel ◽  
Steel Rebars

The number of reinforced concrete structures subject to anoxic conditions such as offshore platforms and geological storage facilities is growing steadily. This study explored the behaviour of embedded steel reinforcement corrosion under anoxic conditions in the presence of different chloride concentrations. Corrosion rate values were obtained by three electrochemical techniques: Linear polarization resistance, electrochemical impedance spectroscopy, and chronopotenciometry. The corrosion rate ceiling observed was 0.98 µA/cm2, irrespective of the chloride content in the concrete. By means of an Evans diagram, it was possible to estimate the value of the cathodic Tafel constant (bc) to be 180 mV dec−1, and the current limit yielded an ilim value of 0.98 µA/cm2. On the other hand, the corrosion potential would lie most likely in the −900 mVAg/AgCl to −1000 mVAg/AgCl range, whilst the bounds for the most probable corrosion rate were 0.61 µA/cm2 to 0.22 µA/cm2. The experiments conducted revealed clear evidence of corrosion-induced pitting that will be assessed in subsequent research.

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