A Model of Cu-CMP

2004 ◽  
Vol 816 ◽  
Author(s):  
Ed Paul ◽  
Vlasta Brusic ◽  
Fred Sun ◽  
Jian Zhang ◽  
Robert Vacassy ◽  
...  
Keyword(s):  
Tungsten Oxide ◽  
Removal Rate ◽  
Formation Rate ◽  
Quantitative Model ◽  
Wafer Surface ◽  
Surface Kinetics ◽  
Oxide Formation ◽  
Mechanical Removal ◽  
High Concentrations ◽  
Oxidizer Concentration

AbstractCMP has been described qualitatively in terms of alternating cycles of chemical formation and mechanical removal of a thin layer on the wafer surface. A quantitative model of CMP has been developed2-7 which is based on mechanisms for surface kinetics, treating mechanical removal as one step in the mechanism. This model has been used successfully to explain removal rates for tungsten and thermal oxide CMP. In particular, for tungsten CMP the removal rate increases steeply with increasing oxidizer concentration at low concentrations, and then approaches an asymptotic maximum removal rate at high concentrations. The model explains this by starting with the assumption that mechanical abrasion removes only tungsten oxide but not tungsten metal. It then focuses on the fraction of wafer surface covered by a tungsten oxide layer. At low oxidizer concentrations, the oxide formation rate is small compared the removal rate, so only a small fraction of the surface is oxidized and the removal rate is small. At high oxidizer concentrations, the oxide formation rate is large compared to the removal rate, so most of the surface is oxidized and the removal rate is large. Increasing the oxidizer concentration in the high oxidizer concentration region does not significantly increase the surface fraction of tungsten oxide, and the removal rate approaches a constant value.

Copper CMP for Dual Damascene Technology: Some Considerations on the Mechanism of Cu Removal

2001 ◽  
Vol 671 ◽  
Author(s):  
David Wei ◽  
Yehiel Gotkis ◽  
Hugh Li ◽  
Stephen Jew ◽  
Joseph Li ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
Removal Rate ◽  
Wafer Surface ◽  
H2o2 Concentration ◽  
Passivation Film ◽  
Mechanical Removal ◽  
Slurry System ◽  
High Removal Rate ◽  
Cu Cmp ◽  
Passivating Oxide

ABSTRACTIt was found in a Cu-CMP process using EP-C 5001 slurry and IC 1000 pad that Cu removal rate, being extremely low without H2O2 in the slurry, increases up to a maximum with the addition of H2O2, and then decreases again. Analysis of polarization curves and Eh-pH diagrams shows that without H2O2 Cu has the lowest electric potential, as a result, the highest thermodynamic stability in the Cu/slurry system. Addition of H2O2 shifts the potential up and induces the formation of Cu2O, resulting in a high removal rate. At high H2O2 concentration, a CuO passivation film is formed. In this case, only mechanical removal of the passivating oxide film allows the process to proceed. It is speculated that the moving pad surface adheres the oxidized species via the formation of hydrogen bonds with oxygen atoms of copper oxide molecules, thus detaching them from the wafer surface. Each oxygen atom is capable of pulling out two Cu atoms if Cu2O is formed on the surface and only one Cu atom if CuO is formed. This would explain why the removal rate is high at low H2O2 concentration and low at high H2O2 concentration.

The influence of ultrasonic vibrations on material removal in the silicon wafer polishing using DDCAMRF: Experimental investigations and process optimization

2021 ◽  
pp. 095440622110389
Author(s):  
Mayank Srivastava ◽  
Pulak M Pandey
Keyword(s):  
Silicon Surface ◽  
Material Removal ◽  
Removal Rate ◽  
Statistical Investigation ◽  
Wafer Surface ◽  
Experimental Investigations ◽  
Ultrasonic Power ◽  
Ultrasonic Vibrations ◽  
Mr Fluid ◽  
Process Factors

The present experimental investigation attempts to understand and address the effect of ultrasonic vibrations on material removal in the polishing of silicon wafers (1 0 0). The requisite finishing experimentations were performed on an indigenously developed experimental arrangement of double-disc chemical assisted magnetorheological finishing (DDCAMRF) process with longitudinal vibrations. The MR fluid used in the experiments consists of a water-based suspension prepared by mixing suitable amounts of carbonyl iron particles (CIPs), abrasive particles, and additives or stabilizers. The prepared MR fluid uses both mechanics and chemistry to finish the silicon surface. Mechanics is mainly responsible for micro-scratching of silicon surface, which gets “softened” by hydration utilizing DI water in the MR fluid. In this study, the ‘response surface methodology (RSM)’ was chosen for designing the experiments to evaluate the significance of different process factors, namely polishing speed, abrasive concentration, and ultrasonic power on the material removal rate (MRR) in DDCAMRF process. The material removed from the wafer surface was measured using the precision digital weighing balance. It was observed that the MRR was found to increase with the increase in various process factors used. Further, analysis of variance (i.e., ANOVA) technique with a 95% confidence interval was performed to analyze the significant contribution of different process factors on MRR. The validation of developed model was done by performing experiments on random and optimized set of process factors. From, the statistical investigation it was discovered that ultrasonic power has highest contribution of 57.9% on MRR, followed by the polishing speed (13.3%), and abrasive concentration (12.5%). Furthermore, a genetic algorithm optimization tool was utilized to obtain optimum set of process parameters to maximize MRR.

scholarly journals Measurements in a highly polluted Asian mega city: observations of aerosol number size distribution, modal parameters and nucleation events

2005 ◽  
Vol 5 (1) ◽  
pp. 57-66 ◽  
Author(s):  
P. Mönkkönen ◽  
I. K. Koponen ◽  
K. E. J. Lehtinen ◽  
K. Hämeri ◽  
R. Uma ◽  
...  
Keyword(s):  
Size Distribution ◽  
Urban Areas ◽  
Geometric Mean ◽  
Formation Rate ◽  
Geometric Standard Deviation ◽  
Modal Parameters ◽  
Number Size Distribution ◽  
High Concentrations ◽  
Rural Sites ◽  
Aitken Mode

Abstract. Diurnal variation of number size distribution (particle size 3-800nm) and modal parameters (geometric standard deviation, geometric mean diameter and modal aerosol particle concentration) in a highly polluted urban environment was investigated during October and November 2002 in New Delhi, India. Continuous monitoring for more than two weeks with the time resolution of 10min was conducted using a Differential Mobility Particle Sizer (twin DMPS). The results indicated clear increase in Aitken mode (25-100nm) particles during traffic peak hours, but towards the evenings there were more Aitken mode particles compared to the mornings. Also high concentrations of accumulation mode particles (>100nm) were detected in the evenings only. In the evenings, biomass/refuse burning and cooking are possible sources beside the traffic. We have also shown that nucleation events are possible in this kind of atmosphere even though as clear nucleation events as observed in rural sites could not be detected. The formation rate of 3nm particles (J3) of the observed events varied from 3.3 to 13.9cm-3s-1 and the growth rate varied from 11.6 to 18.1nmh-1 showing rapid growth and high formation rate, which seems to be typical in urban areas.

scholarly journals Metabolic Capability of Penicillium oxalicum to Transform High Concentrations of Anti-Inflammatory and Analgesic Drugs

2020 ◽  
Vol 10 (7) ◽  
pp. 2479
Author(s):  
Darío Rafael Olicón-Hernández ◽  
Maite Ortúzar ◽  
Clementina Pozo ◽  
Jesús González-López ◽  
Elisabet Aranda
Keyword(s):  
Removal Rate ◽  
Complex Mixture ◽  
Penicillium Oxalicum ◽  
Cytochrome P450 Enzymes ◽  
Batch Bioreactor ◽  
Metabolic Capability ◽  
Inflammatory Drugs ◽  
Anti Inflammatory ◽  
High Concentrations

Non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics are two of the most employed drug groups around the world due to their use in the treatment of edema and pain. However, they also present an ecological challenge because they are considered as potential water pollutants. In this work, the biodegradation of four NSAIDs (diclofenac, ibuprofen, naproxen and ketoprofen) and one analgesic (acetaminophen) at 50 µM (initial concentration) by Penicillium oxalicum, at both flask and bioreactor bench scales, was evaluated. An important co-metabolic mechanism as part of the global bioremediation process for the elimination of these drugs was observed, as in some cases it was necessary to supplement glucose to achieve a 100% removal rate: both individually and as a complex mixture. Identical behavior in the implementation of a fluidized bench-scale batch bioreactor, inoculated with pellets of this fungus and the complex mix of the drugs, was observed. The role of the cytochrome P450 enzymes (CYP) in the biodegradation of the drugs mix were evidenced by the observation of hydroxylated by-products. The results on the reduction of toxicity (micro and phyto) were not conclusive; however, a reduction in phytotoxicity was detected.

Diverting electron fluxes towards sulfate reduction using linoleic acid in a mixed anaerobic culturePaper submitted to the Journal of Environmental Engineering and Science.

2010 ◽  
Vol 37 (11) ◽  
pp. 1492-1504
Author(s):  
Mamata Sharma ◽  
Nihar Biswas
Keyword(s):  
Linoleic Acid ◽  
Sulfate Reduction ◽  
Degradation Rate ◽  
Volatile Fatty Acids ◽  
Removal Rate ◽  
Electron Flow ◽  
Methane Formation ◽  
Sulfate Removal ◽  
Degradation Rates ◽  
High Concentrations

Sulfate (1500 mg/L) reduction and glucose (1870 mg/L) degradation was examined in the presence of five varying linoleic acid (LA) levels (100–1000 mg/L) at 37 ± 2 °C and pH 7.0–7.2. The sulfate reduction and methane formation data suggest that LA selectively inhibited methane producing bacteria (MPB). The quantity of sulfate removed increased with increasing LA dosage. Approximately 1375 mg/L (92%) sulfate was removed in cultures fed with high concentrations of LA (1000 mg/L), which was 68% more than that removed in glucose and sulfate controls. The quantity of sulfate removed in cultures fed with 100, 300, 500 and 700 mg/L LA were 62%, 66%, 77%, and 84%, respectively. Initial sulfate degradation rates increased with increasing LA levels in the cultures. High LA levels (1000 mg/L) attributed to approximately a sevenfold increase in the initial sulfate degradation rates compared to cultures containing sulfate plus glucose. The highest initial sulfate removal rate (0.19 µg/(mgVSS min)) was observed in cultures receiving 1000 mg/L LA. Initial glucose degradation rates decreased with increasing LA concentrations. The rates for the cultures receiving 1000 mg/L LA were 2.53 µg/(mgVSS min) while the degradation rate for cultures containing 100 mg/L LA was 5.40 µg/(mgVSS min). Methane formation decreased when sulfate and LA were added. Methane formation was lowest in cultures receiving elevated LA concentrations. The percent electron flow fluxes increased towards sulfidogenesis and decreased towards methanogenesis with increasing LA levels. Less than 0.6% electron flow was diverted to methanogenesis in cultures containing high levels of LA (≥700 mg/L) while ≤ 45% was diverted to sulfidogenesis. Acetate and propionate were the major volatile fatty acids (VFAs) detected during glucose degradation. The amount of sulfate reduced in the cultures receiving only LA or sulfate and no other carbon source was comparable (approximately 10%), which suggests that LA did not contribute to electrons during the course of experiment for sulfate reduction.

Study on Chemical Mechanical Polishing Technology of Copper

2008 ◽  
Vol 373-374 ◽  
pp. 820-823
Author(s):  
Sheng Li Wang ◽  
Y.J. Yuan ◽  
Yu Ling Liu ◽  
X.H. Niu
Keyword(s):  
Chemical Mechanical Polishing ◽  
Colloidal Silica ◽  
Removal Rate ◽  
Mechanical Polishing ◽  
Alkali Concentration ◽  
Copper Films ◽  
Optimum Conditions ◽  
Slurry Flow Rate ◽  
Polishing Pressure ◽  
Oxidizer Concentration

Chemical mechanical polishing (CMP) of copper films in alkaline slurries was investigated. In the copper CMP, the slurry was made by adding colloidal silica abrasive to de-ionized water.The organic alkali was added to adjust the pH, H2O2 was used as an oxidizer.The effects of varying polishing temperature, polishing pressure, slurry flow rate, organic alkali concentration and oxidizer concentration on removal rate were investigated in order to determine the optimum conditions for those parameters. It is shown the chemical composition of the slurry was 2%~3% oxidizer concentration, 3% organic alkali concentration and proper amount surfactant is reasonable. The solid concentration of the polishing slurry was fixed at 20% by weight. The removal rate of copper could reach 700nm/min and the surface roughness after CMP was 0.49nm.

Simultaneous heterotrophic nitrification and aerobic denitrification at high concentrations of NaCl and ammonia nitrogen by Halomonas bacteria

2017 ◽  
Vol 76 (2) ◽  
pp. 386-395 ◽  
Author(s):  
Te Wang ◽  
Jian Li ◽  
Ling Hua Zhang ◽  
Ying Yu ◽  
Yi Min Zhu
Keyword(s):  
Removal Rate ◽  
Sodium Succinate ◽  
Bacterial Genome ◽  
Ammonia Nitrogen ◽  
Compatible Solute ◽  
Heterotrophic Nitrification ◽  
Aerobic Denitrification ◽  
Sequencing Analysis ◽  
N Removal ◽  
High Concentrations

To improve the efficiency of simultaneous heterotrophic nitrification and aerobic denitrification (SND) at high concentrations of NaCl and ammonia nitrogen (NH4+—N), we investigated the SND characteristics of Halomonas bacteria with the ability to synthesize the compatible solute ectoine. Halomonas sp. strain B01, which was isolated, screened and identified in this study, could simultaneously remove nitrogen (N) by SND and synthesize ectoine under high NaCl conditions. Gene cloning and sequencing analysis indicated that this bacterial genome contains ammonia monooxygenase (amoA) and nitrate reductase (narH) genes. Optimal conditions for N removal in a solution containing 600 mg/L NH4+–N were as follows: sodium succinate supplied as organic carbon (C) source at a C/N ratio of 5, pH 8 and shaking culture at 90 rpm. The N removal rate was 96.0% under these conditions. The SND by Halomonas sp. strain B01 was performed in N removal medium containing 60 g/L NaCl and 4,000 mg/L NH4+–N; after 180 h the residual total inorganic N concentration was 21.7 mg/L and the N removal rate was 99.2%. Halomonas sp. strain B01, with the ability to synthesize the compatible solute ectoine, could simultaneously tolerate high concentrations of NaCl and NH4+–N and efficiently perform N removal by SND.

Effects of Wafer Carrier Design on Contact Stress Uniformity in CMP

2010 ◽  
Vol 126-128 ◽  
pp. 305-310 ◽  
Author(s):  
Ian Hu ◽  
Tian Shiang Yang ◽  
Kuo Shen Chen
Keyword(s):  
Contact Stress ◽  
Removal Rate ◽  
Ring Width ◽  
Pressure Profile ◽  
Back Pressure ◽  
Design Parameters ◽  
Wafer Surface ◽  
Retaining Ring ◽  
Floating Type ◽  
Stress Uniformity

Here we use 2-D models of fluid film lubrication and contact mechanics to calculate the contact stress and fluid (i.e., slurry) pressure distributions on the wafer–pad interface in CMP. In particular, the effective rigidity of the wafer (determined by the wafer carrier structure), the retaining ring width and its back pressure are taken to be the design parameters. The purpose is to study the synergetic effects of such parameters on the contact stress non-uniformity (NU), which directly affects the spatial non-uniformity of the material removal rate on the wafer surface. Our numerical results indicate that, for a given wafer rigidity, one may choose a particular combination of the retaining ring parameters to minimize NU. Also, the corresponding minimum NU decreases with the effective wafer rigidity, suggesting that it is beneficial to use a soft (e.g., floating-type) wafer carrier. Moreover, for a soft wafer carrier, the presence of the retaining ring also reduces NU to some extent, but the use of a multi-zone wafer-back pressure profile would be more effective in this regard.

Study on Grinding Performance of Soft Abrasive Wheel for Silicon Wafer

2009 ◽  
Vol 416 ◽  
pp. 529-534 ◽  
Author(s):  
Ren Ke Kang ◽  
Shang Gao ◽  
Zhu Ji Jin ◽  
Dong Ming Guo
Keyword(s):  
Silicon Wafer ◽  
Chemical Reaction ◽  
Removal Rate ◽  
Surface Damage ◽  
Amorphous Layer ◽  
Diamond Wheel ◽  
Wafer Surface ◽  
Abrasive Wheel ◽  
Grinding Performance ◽  
Diamond Abrasive

With the development of IC manufacturing technology, the machining precision and surface quality of silicon wafer are proposed much higher, but now the planarization techniques of silicon wafer using free abrasive and bonded abrasive have the disadvantage of poor profile accuracy, environmental pollution, deep damage layer, etc. A soft abrasive wheel combining chemical and medical effect was developed in this paper, it could get super smooth, low damage wafer surface by utilizing mechanical friction of abrasives and chemical reaction among abrasives, additives, silicon. A comparison experiment between #3000 soft abrasive wheel and #3000 diamond abrasive wheel was given to study on the grinding performance of soft abrasive wheel. The results showed that: wafer surface roughness ground by soft abrasive wheel was sub-nanometer and its sub-surface damage was only 0.01µm amorphous layer, which were much better than silicon wafer ground by diamond abrasive wheel, but material removal rate and grinding ratio of soft abrasive wheel were lower than diamond wheel. The wafer surface ground by soft abrasive wheel included Ce4+, Ce3+, Si4+, Ca2+ and Si, which indicated that the chemical reaction really occurred during grinding process.

Surface Effects and Residual Stresses in Electrolytically Ground Steel

1962 ◽  
Vol 84 (4) ◽  
pp. 483-489 ◽  
Author(s):  
J. Frisch ◽  
R. R. Cole
Keyword(s):  
Residual Stress ◽  
Corrosion Resistance ◽  
Residual Stresses ◽  
Material Removal ◽  
Removal Rate ◽  
Stress Distributions ◽  
Electrolyte Flow ◽  
Surface Conditions ◽  
Mechanical Removal ◽  
Grinding Conditions

The effects of electrolytic grinding on surface conditions and residual stress characteristics has been experimentally investigated. Surface finish, uniformity of material removal, and corrosion resistance are found to be dependent on mechanical removal rate as determined by wheel downfeed as well as electrolyte flow rate. Downfeeds of approximately 0.002 in. in the process do not produce measurable residual stresses and therefore it was further established that electrolytic grinding with moderate downfeeds can be used in place of swab etching techniques for evaluation of residual stress distributions. The maximum residual surface stresses were found to be not more than 22,000 psi, well below the yield strength of the material and were induced during the most severe grinding conditions.

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