Dilution Of Slurry Research Articles

CMP characteristics of IGZO thin film with a variety of process parameters

Recently, amorphous indium gallium zinc oxide (a-IGZO) has been studied in the field of 3D transistors as a channel material for high mobility, good uniformity, and low leakage current performance. The CMP process needs to be applied to fully remove surface IGZO in a multilayer film stack structure and achieve the purpose of planarization. As we all know, the CMP characteristics of the desired removal rate with stability and within-wafer non-uniformity (WIWNU%) play an important role in the CMP process. In this paper, the variation of the removal rate and the non-uniformity for IGZO thin film were studied with various process parameters (such as polishing time, slurry flow rate, slurry dilution, head pressure, head and table speed). The results mean that the removal rate and the non-uniformity of IGZO thin film can be tuned by changing process parameters, which can enhance the confidence about the feasibility of IGZO-CMP in the application of advanced technology.

Peering into a Simplified Digestor for Households: Performance, Cost and Carbon-Neutral Niche

In this study, a black-shading cylindrical water tank made of high-density polyethylene was locally manufactured as a household digestor for treating cow manure in Bangladesh. Effluent slurry instead of water was reused for manure dilution under manure-to-slurry ratios of 1:2 and 1:1, to assess this small prototype’s production efficiency and feasibility. The specific biogas production at both ratios matched well, by 0.12 m3/kg VS and 0.14 m3/kg VS, respectively, while the former slurry dilution operation outperformed in daily and accumulative biogas production by 16% and 57%, correspondingly, referring to 0.49 Nm3/d on average and 8.55 Nm3 in total, potentially meeting a 2 h household cooking energy requirement. From a nationwide viewpoint, slurry dilution was proven to be a great initiative to conserve water amounting to 50,286,751 m3 for 114,810 households of 6 person-equivalents annually, while cutting chemical costs by USD 32,720,684/yr and trimming annual greenhouse gas emission by 1.8 million tons of CO2e. This study revealed that a small prototype digestor could be an alternative energy source for cost-effective and eco-friendly household applications.

Biocrust Amendments to Topsoils Facilitate Biocrust Restoration in a Post-mining Arid Environment.

Soil cryptogamic biocrusts provide many ecological functions in arid zone ecosystems, though their natural reestablishment in disturbed areas is slow. Accelerating reestablishment of biocrusts may facilitate the establishment of vascular plant communities within the timeframes of restoration targets (typically 5–15 years). One technique is to inoculate the soil surface using slurries of biocrust material harvested from another site. However, this is destructive to donor sites, and hence the potential to dilute slurries will govern the feasibility of this practice at large spatial scales. We conducted a replicated experiment on a disturbed mine site to test the individual and combined effects of two strategies for accelerating soil cryptogamic biocrust reestablishment: (1) slurry inoculation using biocrust material harvested from native vegetation; and (2) the use of psyllium husk powder as a source of mucilage to bind the soil surface, and to potentially provide a more cohesive substrate for biocrust development. The experiment comprised 90 experimental plots across six treatments, including different dilutions of the biocrust slurries and treatments with and without psyllium. Over 20 months, the reestablishing crust was dominated by cyanobacteria (including Tolypothrix distorta and Oculatella atacamensis), and these established more rapidly in the inoculated treatments than in the control treatments. The inoculated treatments also maintained this cover of cyanobacteria better through prolonged adverse conditions. The dilute biocrust slurry, at 1:100 of the biocrust in the remnant vegetation, performed as well as the 1:10 slurry, suggesting that strong dilution of biocrust slurry may improve the feasibility of using this technique at larger spatial scales. Psyllium husk powder did not improve biocrust development but helped to maintain a soil physical crust through hot, dry, and windy conditions, and so the potential longer-term advantages of psyllium need to be tested.

Long-term incubations provide insight into the mechanisms of anaerobic oxidation of methane in methanogenic lake sediments

Abstract. Anaerobic oxidation of methane (AOM) is among the main processes limiting the release of the greenhouse gas methane from natural environments. Geochemical profiles and experiments with fresh sediments from Lake Kinneret (Israel) indicate that iron-coupled AOM (Fe-AOM) sequesters 10 %–15 % of the methane produced in the methanogenic zone (>20 cm sediment depth). The oxidation of methane in this environment was shown to be mediated by a combination of mcr-gene-bearing archaea and pmoA-gene-bearing aerobic bacterial methanotrophs. Here, we used sediment slurry incubations under controlled conditions to elucidate the electron acceptors and microorganisms that are involved in the AOM process over the long term (∼ 18 months). We monitored the process with the addition of 13C-labeled methane and two stages of incubations: (i) enrichment of the microbial population involved in AOM and (ii) slurry dilution and manipulations, including the addition of several electron acceptors (metal oxides, nitrate, nitrite and humic substances) and inhibitors (2-bromoethanesulfonate, acetylene and sodium molybdate) of methanogenesis, methanotrophy and sulfate reduction and sulfur disproportionation. Carbon isotope measurements in the dissolved inorganic carbon pool suggest the persistence of AOM, consuming 3 %–8 % of the methane produced at a rate of 2.0 ± 0.4 nmol per gram of dry sediment per day. Lipid carbon isotopes and metagenomic analyses point towards methanogens as the sole microbes performing the AOM process by reverse methanogenesis. Humic substances and iron oxides, although not sulfate, manganese, nitrate or nitrite, are the likely electron acceptors used for this AOM. Our observations support the contrast between methane oxidation mechanisms in naturally anoxic lake sediments, with potentially co-existing aerobes and anaerobes, and long-term incubations, wherein anaerobes prevail.

Dilution rates of cattle slurry affect ammonia uptake and protein production of duckweed grown in recirculating systems

Duckweed is a potential collector of nitrogen from animal liquid manure and a source of protein suitable as feed for livestock and fish. Therefore, it provides opportunities for circular economy systems. Two duckweed species, Spirodela polyrhiza and Landoltia punctata, were grown in five recirculating systems each connected to a reservoir tank filled with water and graded organic cattle slurry concentrations. Fresh and dry biomass, protein production and amino acid profiles among the nitrogen removal were evaluated. Spirodela polyrhiza showed a significantly higher fresh biomass production but L. punctata dry matter content was generally higher resulting in similar dry biomass production for both species This study shows clearly that the crude protein content, ranging between 29.3 and 37.9% of dry matter, was positively correlated to slurry and total ammonia nitrogen (TAN) concentration of the substrate, independent of the duckweed species. Total crude protein yield was in the range of 1.37–1.95 g m−2 d−1, following a quadratic function regarding slurry and TAN concentrations, with marginal differences between species. Biomass and crude protein yields were optimal for both duckweed species at a TAN concentration of 19 mg l−1, which corresponded to a slurry dilution of 1:8. The results of this study provide important information for operation of recirculating duckweed production systems on slurry and operators should aim to keep TAN concentrations in that range for optimization of protein production in conjunction with TAN removal.

Correction to: Effect of feed slurry dilution and total solids on specific biogas production by anaerobic digestion in batch and semi-batch reactors

Correction to: Effect of feed slurry dilution and total solids on specific biogas production by anaerobic digestion in batch and semi-batch reactors

Effect of feed slurry dilution and total solids on specific biogas production by anaerobic digestion in batch and semi-batch reactors

Biomass from various sources such as cow dung is a significant source of renewable energy (as biogas) in many regions globally, especially in India, Africa, Brazil, and China. However, biogas production from biomass such as cattle dung is a slow, inefficient biochemical process, and the specific biogas produced per kg of biomass is relatively small. The improvement of specific biogas production efficiency using various dilution ratios (and, hence, total solids [TS]) is investigated in this work. A wide range of feed dilution (FD) ratios of cow dung: water (CD: W) was tested in batch biogas digesters with total solids ranging from 1% to 12.5% and FD ratio ranging from 2:1 to 1:20. To further verify the results from the above batch experiments, semi-batch experiments representative of field-scale biodigesters were conducted. Semi-batch reactors have a steady-state process, unlike batch reactors, which have an unsteady state process. Our results suggested that specific biogas production (mL/g VS) increased continuously when the total solids decreased from 12.5% to 1% (or when dilution increased). Our experiments also indicate that the commonly used 1:1 feed dilution ratio (TS ~ 10% for cow dung) does not produce the maximum specific biogas production. The possible reason for this could be that anaerobic digestion at higher total solids is rate limited due to substrate inhibition, mass transfer limitations, and viscous mixing problems that arise at higher total solids concentration. Hence, a higher feed dilution ratio between 1:2 and 1:4 (TS between 4 and 6.7%) is recommended for a more efficient biomass utilization of cowdung. Empirical relationships were also developed for variation of specific biogas yield with the total solids content of the cow dung slurry.Graphic abstract

Enabling pseudo-ductility in geopolymer based glass-ceramics matrix composites by slurry dilution

Carbon fibre reinforced composites with matrix consisting of porous glass-ceramics obtained by high temperature heat-treatment of geopolymer based material are studied. The matrix is obtained from a slurry. Several composites have been manufactured by in-laboratory stratification of pre-impregnated plies with slurries diluted at various rates. Slurry dilution changes the porosity and leads to pseudo-ductile behaviour of the composite. Dilution implies a drop of non-linearity stress threshold together with a slower decrease of the strength. An optimal dilution rate is evidenced, which exhibits high strength but lower non-linearity stress threshold, and then, a significant failure strain. The optimized prepreg material is compared with a reference composite processed by an industrial prepreg process. The origin of the pseudo-ductility is related to decohesion at the interface between tows and inter-tow matrix. RTM also provides a pseudo-ductile composite but with very low non-linearity stress threshold, in relation to poorly impregnated tows.

Anaerobic digestion of dissolved air floatation slurries: Effect of substrate concentration and pH

Dissolved air floatation (DAF) slurries are an unconventional substrate for anaerobic digestion owing to their high COD concentrations, mainly consisting of lipids. Batch anaerobic digestion of DAF slurry was conducted to investigate the methane production through dilution of the slurry (with mineral salt medium, MSM) and by adjusting the initial pH (to 6.0, 5.5, 5.0 and 4.5) The performance of two different inocula, namely waste activated sludge (WAS) treating domestic wastewater and anaerobic granular sludge (AGS) treating dairy wastewater, was compared. The DAF slurry had a pH of 7.03 ( ± 0.07), conductivity of 6.69 ( ± 0.54) mS/cm, and a COD and ammonium concentration of 85.96 ( ± 8.32) g/L and 168.49 ( ± 1.79) mg N/L, respectively. DAF slurry without dilution produced a maximum methane yield of 58.60 ( ± 1.97) mL/g COD after 30 days of incubation. Dilution with MSM up to three folds, improved the methane yield by about 67%–105% and 67%–177% with WAS and AGS as the inoculum, respectively. Higher methane productivity was achieved at an inoculum to substrate ratio of at least 1.5 for WAS and 2.0 for AGS, respectively. AGS was more effective with a 20% increase in methane production from 3-fold diluted DAF slurry when compared with WAS. Adjustment of the initial pH of the DAF slurry to 6.0 resulted in a methane yield of 359.71 ( ± 32.72) mL/g COD, which was 23% higher than the control without pH adjustment. This study demonstrated that the methane yield from DAF slurries can be enhanced through substrate dilution and initial pH adjustment. • Methane yield enhanced by 23% upon adjustment of initial pH of the DAF slurry to 6.0. • 3-fold dilution increased methane production rate by 275% with granular sludge. • Anaerobic granular sludge is an efficient inoculum for methanogenesis of DAF slurry. • Lag phase duration was not shortened by dilution or pH adjustment of the DAF slurry. • Optimal inoculum to substrate ratio at least 1.5 and 2.0 for WAS and AGS, respectively.

Cost-effectiveness of environmental impact abatement measures in a European pig production system

Many emerging technologies and alternative farm management practices have the potential to improve the sustainability of pig production systems. The implementation of such practices is not always economically viable. The goal of this study was to assess the cost-effectiveness of such environmental mitigation strategies in pig systems, using an Environmental Abatement Cost analysis. We considered four pig housing (improved insulation, increased ventilation efficiency, frequent slurry removal, increased slurry dilution) and three manure management related abatement strategies (anaerobic digestion, slurry acidification, slurry separation), implemented as stand-alone and as a set of “pig housing–pig housing” and “pig housing–manure management” combinations. We calculated their annual equivalent value through a discounted cash flow analysis and then their annualised abatement potential through a cradle-to-farm gate life cycle assessment. The baseline system against which the analysis was conducted was a typical Danish pig production system, over a 25-year time horizon. The environmental impact categories considered were Non-Renewable Resource Use (NRRU), Non-Renewable Energy Use (NREU), Global Warming Potential (GWP), Acidification Potential (AP) and Eutrophication Potential (EP). Pig housing–anaerobic digestion combinations were the most cost-effective options for GWP, NRRU and NREU. Their abatement costs ranged from −€0.237 to €0.70 per tonne CO2 eq., −€0.146 to €0.36 per g Sb eq. and -€1.75−04 to €3.11−04 per GJ abated respectively. Anaerobic digestion was the most cost-effective stand-alone investment for GWP (−€0.206 per tonne CO2 eq.), NRRU (−€0.0493 per g Sb eq.) and NREU (−€1.00−04 per GJ), and slurry acidification for AP (€303 per tonne SO2− eq.) and EP (€1190 per tonne PO43− eq.) mitigation. Overall, measures for mitigation of GWP, NRRU and NREU required higher investments than for AP and EP, but also generated profit. The framework developed in this study can potentially aid decision making in the choice of environmentally and economically sustainable pig system modifications.

Environmental impacts of housing conditions and manure management in European pig production systems through a life cycle perspective: A case study in Denmark

The potential of modifications in the housing conditions and manure management to reduce the environmental impact of a European pig production system were evaluated. The study was carried out using a cradle-to-farm gate life cycle assessment (LCA), with a functional unit of 1 kg of live weight pig at farm gate. The study used Danish pig systems as a case in point, with data provided by the Danish Pig Research Centre (SEGES).Potential environmental impact hotspots at pig housing and manure management were identified through a local sensitivity analysis. A set of pig housing and manure management alternative scenarios were analysed using parallel Monte Carlo simulations, to quantify interactions between these two components of the system. The manure management scenarios were slurry acidification, screw-press slurry separation and centralised anaerobic digestion of slurry. The pig housing scenarios were constructed around variations of the following factors: i) level of barn insulation, ii) in-barn temperature, iii) ventilation efficiency, iv) level of slurry dilution and v) frequency of slurry removal from barn pits.Anaerobic digestion significantly reduced the environmental impact for Non-Renewable Resource Use (−34.1% compared to baseline), Non-Renewable Energy Use (−40.1%) and Global Warming Potential (−9.20%). Slurry acidification led to significant reductions in Acidification (−28.1%) and Eutrophication Potential (−14.2%). Slurry separation significantly reduced only Non-Renewable Energy Use (−2.26%).The scenario analysis showed that the environmental performance of all manure management alternatives was affected by variations in all housing related factors, except for in-barn temperature. The largest improvement in environmental performance of the manure management component was achieved for Acidification Potential (−5.51%) by increasing the level of slurry dilution under baseline manure management conditions. Slurry acidification was the least sensitive manure management alternative to modifications in pig housing. Both manure management and housing conditions have the potential to reduce the environmental impact of pig systems in Europe.

Uji Kinerja Unit Mesin Pasteurisasi Tipe Kontinyu untuk Pengolahan Sari Buah Sirsak

Soursop fruit is one of the horticultural products that are easily damaged after the maturation process. This fruit is generally consumed in the form of fresh ripe or juice. The quality of the fruit is also very diverse and at harvest time the amount is abundant so the selling price tend to be low. One alternative to increase the added value of soursop fruit which the quality is poor and to extend the shelf life can be done through processing into juice. This study aims to test the performance of continuous type pasteurizer unit which has been developed by the Indonesian Center for Agricultural Engineering research and Development (ICAERD) in the processing of soursop juice on a small scale industry. The pasteurizer unit consists of a mixer, pasturizer, holder, filler, and cup sealer. The process of soursop juice processing includes fruit bunching, skin peeling, burial, mixing and dilution of slurry, fruit juice pasturization, and packaging. The pasteurization process was done at 80 ºC for 5-10 minutes. The pasteurization temperature is achieved at pavor pressure on water heating tube of about 1.0-1,5 bar. Under these conditions the capacity of continuous type pasteurizer unit was 160 l/h. The resulting juice has a TPC content on days 0, 7, and 14 after storage was 4.8 x 102, 5.1 x 102, and 1.9 x 103 cfu/g, respectively. The heavy metal content of Cu and Pb were 0.63 and 0.29 ppm, respectively.Keywords: performance test, pasteurizer, continuous type, soursop juice processing, value added product.

Application of a Slurry Injection System to Cobalt “Buff Step” Chemical Mechanical Planarization

This study investigates the effects of a novel slurry injection system on the thermal, tribological, and kinetic aspects of new middle of the line cobalt “buff step” CMP process. The mean pad temperature, coefficient of friction (COF) and removal rate were higher when applying the slurry using the novel injection system compared to the standard point application method. By using the novel slurry injection system, the overall consumption of slurry could be reduced by 25 to 33% compared to the slurry consumed by the point application method, while still achieving similar removal rates. Our well-established modified two-step Langmuir-Hinshelwood model apparently failed when it was used to simulate the removal rates using the activation energy and optimized parameters from our previous work with the same slurry. By making a small alteration (e.g. by optimizing the pre-exponential factor for the Arrhenius chemical rate constant for each different flow rate and slurry application method) to account for slurry dilution by residual rinse water and spent slurry, the model was able to successfully simulate experimental removal rates.

Effect of Various Slurry Injection System Configurations on Removal Rates of Silicon Dioxide Using a Ceria-Based Chemical Mechanical Planarization Slurry

In this work, the position of the novel slurry injection system (SIS) was optimized to achieve a more cost-effective and environmentally benign chemical mechanical planarization process using a widely-adopted ceria-based “reverse slurry”. SIS was configured with different angles in order to investigate slurry dilution characteristics caused by residual pad rinsing with ultrapure water (UPW) that affected silicon dioxide removal rates. UPW dilution effect on removal rate, coefficient of friction and pad surface temperature was explained by maintaining a constant dilution ratio for each of the SIS configuration tests. Results indicated that the negative rotation angle of the SIS increased the actual slurry dilution ratio on top of the polishing pad. This generated more Ce3+ which boosted the removal rate. Application of negatively rotated SIS allowed significantly lower slurry flow rate and/or shorter polishing time leading to achieve a more environmental friendly semiconductor manufacturing process. Finally, it was confirmed that variations in SIS configuration had no impact on silicon dioxide to silicon nitride removal rate selectivity.

Effect of Conditioning and Slurry Application Method on Silicon Dioxide Removal Rates Using a Ceria-Based Chemical Mechanical Planarization Slurry

In this study, the silicon dioxide removal rate using a “reverse” ceria-based slurry was investigated under four different combinations of conditioning modes and slurry application methods. In a “reverse” slurry, addition of water acts to promote material removal. Overall, the process using ex-situ conditioning with the slurry injection system (SIS) resulted the highest removal rate, while the process using in-situ conditioning with the conventional point application (PA) generated lowest removal rate. This study is aimed to explain the differences in silicon dioxide removal rate based on the variations of the actual slurry dilution ratio on top of the pad associated with conditioning and slurry application methods. The frictional analysis and Stribeck+ curves were employed to elucidate the tribological characteristics. The results showed that the conditioning modes and the slurry application methods varied the extent of the polishing vibrations. The silicon dioxide removal rate was found to linearly correlate with the extent of COF fluctuation. This work also underscored the importance of optimum slurry flow dynamics and injection geometry for obtaining a more cost-effective and environmentally benign chemical mechanical planarization process.

Microwave synthesis of delaminated acid saponites using quaternary ammonium salt or polymer as template. Study of pH influence

Mesoporous saponites were prepared at pH8 and 13 without and with template (surfactant or polymer) at 453K and autogenic pressure using microwaves or conventional oven during the hydrothermal ageing treatment. Acidity was obtained by calcination of the NH4-form. The effect of dilution (H2O/Si molar ratios of 250, 125 and 50) was studied for the samples prepared at pH8 with surfactant. In order to compare the effect of introducing surfactant during or after saponite synthesis, several samples prepared at pH13 were modified after synthesis by refluxing or by stirring at room temperature in a surfactant solution. Preparation of samples at pH13 favoured the ordering in the stacking direction, improved AlT/AlO ratio and led to samples with lower amorphous siliceous material content. The use of microwaves and surfactant for the synthesis at pH13 afforded a saponite with the highest surface area (603m2/g) and the smallest lamellae crystallite size (about 4nm). The properties of the samples synthesized at pH8 with surfactant depended on the dilution. Thus, the degree of delamination, the BET area and the AlT/AlO ratio increased whereas the amorphous siliceous material content decreased at lower slurry dilution. The incorporation of the surfactant by post-synthesis resulted in some degree of delamination especially when using refluxing. However, the degree of delamination was higher for the saponites prepared with the addition of the surfactant during the hydrothermal synthesis.

Estimation and Attribution of Nitrous Oxide Emissions Following Subsurface Application of Animal Manure: A Review

Abstract. Field studies demonstrate increased ammonia (NH3) abatement efficiencies (up to 90%) of subsurface application and incorporation of animal manures compared to conventional surface application methods. However, a portion of the nitrogen (N) conserved may come at the expense of increased nitrous oxide (N2O) emissions produced during denitrification and nitrification processes in the soil. Research of N2O emissions subsequent to subsurface manure application is limited (particularly in the U.S.) and results are variable. Cumulative N2O emissions typically range from 0.1% to 3% of the total N applied following manure injection; however, only a few studies indicate a statistical difference in N2O emissions when compared to surface application methods. Circumstances attributed to increased emissions vary among studies and include the concentration of readily metabolizable water-soluble carbon (C) in manure slurry compared to background levels in the soil, soil moisture conditions pre- and post-subsurface application that drive nitrification and denitrification processes, localized N form and oxygen (O2) concentration at the injection site, and injection depth, which can dictate the length of the diffusion path of N2O to the atmosphere. Research also draws correlations of N2O emission rates with subsurface application method, atmospheric conditions during and subsequent to application, and solids separation and dilution of manure slurry. Results thus far suggest that increased N2O emission is not an inevitable consequence of NH3 abatement strategies and should not dissuade subsurface manure application practices. Furthermore, potential reductions in indirect N2O emissions may be realized with subsurface application methods when compared to high NH3 volatilization and N deposition associated with surface application methods. Considering these tradeoffs and the ongoing debate on the role of anthropogenic greenhouse gases such as N2O and their role in climate change warrants more investigation of the factors that contribute to N2O emissions. This review synthesizes the available research on N2O emissions following subsurface application of animal manure to both grassland and arable land, compares results from different application techniques, and examines the conditions and circumstances that lead to N2O emissions.

Pyrolysis kinetics of algal consortia grown using swine manure wastewater

In this study, pyrolysis kinetics of periphytic microalgae consortia grown using swine manure slurry in two seasonal climatic patterns in northwest Arkansas were investigated. Four heating rates (5, 10, 20 and 40°Cmin−1) were used to determine the pyrolysis kinetics. Differences in proximate, ultimate, and heating value analyses reflected variability in growing substrate conditions, i.e., flocculant use, manure slurry dilution, and differences in diurnal solar radiation and air temperature regimes. Peak decomposition temperature in algal harvests varied with changing the heating rate. Analyzing pyrolysis kinetics using differential and integral isoconversional methods (Friedman, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose) showed strong dependency of apparent activation energy on the degree of conversion suggesting parallel reaction scheme. Consequently, the weight loss data in each thermogravimetric test was modeled using independent parallel reactions (IPR). The quality of fit (QOF) for the model ranged between 2.09% and 3.31% indicating a good agreement with the experimental data.

Decision Support for the Construction of Farm-Scale Biogas Digesters in Developing Countries with Cold Seasons

Biogas production is a clean renewable energy source that can improve lives in developing countries. However, winter temperatures in some areas are too low to enable enough biogas production in small unheated digesters to meet the energy requirements of households. Low-cost, high yield reactors adapted to the local climate are needed in those situations. A decision-support model was developed to assist in the design of biogas reactors capable of meeting households’ year-round energy needs. Monthly biogas production relative to household energy needs was calculated for the scenario of suburban Hanoi, Vietnam. Calculations included pig number, slurry (manure water mixture) dilution, retention time and biogas/solar heating. Although using biogas to heat the digester increased biogas production, it did not lead to an energy surplus, particularly with the 1:9 slurry dilution rate commonly used on pig farms. However, at a 1:3 slurry dilution, the use of solar heating to provide 90% and biogas 10% of the heat required to heat the digester to 35 °C improved the biogas production by 50% compared to psychrophilic production. The energy needs of an average five-person family throughout the year required 17 fattening pigs. This model can establish the best solution for producing sufficient energy throughout the year.

(Invited) GST CMP Challenges and Solutions for 45nm PCRAM

We report on GST(Ge2Sb2Te5) CMP process challenges and solutions in this paper. GST stain issue is solved through proper polish pad selection, process scheme and cleaning step optimization. The key factors to achieve minimum oxide loss are slurry dilution ratio & H2O2 concentration optimization and over polish control. Pico-second laser acoustics type measurement tool proves suitable for GST CMP process inline and offline monitor