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Solution-based processes have received considerable attention in the fabrication of electronics and sensors owing to their merits of being low-cost, vacuum-free, and simple in equipment. However, the current solution-based processes either lack patterning capability or have low resolution (tens of micrometers) and low pattern fidelity in terms of line edge roughness (LER, several micrometers). Here, we present a surface energy-directed assembly (SEDA) process to fabricate metal oxide patterns with up to 2 orders of magnitude improvement in resolution (800 nm) and LER (16 nm). Experiment results show that high pattern fidelity can be achieved only at low relative humidities of below 30%. The reason for this phenomenon lies in negligible water condensation on the solution droplet. Employing the SEDA process, all-solution-processed metal oxide thin film transistors (TFTs) are fabricated by using indium oxide as channel layers, indium tin oxide as source/drain electrodes and gate electrodes, and aluminum oxide as gate dielectrics. TFT-based logic gate circuits, including NOT, NOR, NAND, and AND are fabricated as well, demonstrating the applicability of the SEDA process in fabricating large area functional electronics.

Eddy-current sensor systems have been employed to determine the real-time thickness distribution of metal films and the thickness at endpoint detection in metal chemical mechanical polishing (CMP) processes, to achieve global planarization and avoid overpolishing or underpolishing. However, the large lift-off distance of 3.5 mm between the sensor coil and metal film gradually decreases with continuous wear of the polishing pad, which has a strong negative impact on the sensitivity and accuracy of the thickness measurement. In this study, a double-coil eddy-current sensor system, with novel characteristic ratio detection capability, is proposed for metal film thickness measurement and compared with a traditional amplitude-based method. The linear relationship between the characteristic ratio and metal film thickness that is immune to lift-off distance is demonstrated both theoretically and experimentally. The experimental results show that the proposed method performs better than the amplitude-based method, reducing the effect of lift-off distance variation and obtaining an excellent linear measurement range from 24 to 2095 nm. The measurement accuracy is as high as 2.1 nm with an excitation frequency of 1.39 MHz and a large lift-off distance of 3.5 mm. The relative measurement error is less than 1.2% and the endpoint thickness ranges from 100 to 180 nm in the Cu-CMP process, when the lift-off distance varies from 3.6 to 3.3 mm.

Straw is widely incorporated into soil worldwide, but most studies have concentrated on the effects of straw mulching or incorporation with topsoil. To determine the effect of depth of straw incorporation on bacterial and fungal communities, we established a field experiment in a region in Northeast China with Haplic Chernozems using four treatments: conventional tillage (CT, tillage to a depth of 15 cm with no straw incorporation), straw incorporation with conventional tillage (SCT, tillage to a depth of 15 cm), inversion tillage (IT, tillage to a depth of 35 cm) and straw incorporation with inversion tillage (SIT, tillage to a depth of 35 cm). The soils were managed by inversion to a depth of 15 or 35 cm after harvest. The results show that soil organic carbon content was significantly higher and pH and bulk density were significantly lower in the 15–35 cm layer in IT and SIT than CT and SCT. Fungal abundance was higher with straw incorporation, but fungal diversity was lower in the 0–15 cm layer in SCT and SIT than in CT and IT. Path length in the bacterial network was shorter and connectivity was higher in CT + SCT than in IT + SIT, leading to a more complex ecosystem, and the fungal network had opposite patterns. The key taxa in the phylum Actinobacteriota and Ascomycota in the microbial networks changed dramatically at the genus level following inversion tillage with straw amendment, which may increase bacterial network resistance to environmental disturbances and unstable fungal networks, resulting in large changes in the fungal community involved in the decomposition of recalcitrant straw-derived C and the more efficient acquisition of limiting resources.

Abstract: The synthesis of CeO2nanoparticles for CeO2based slurry gains continuous emphasis on improving its performance in the chemical mechanical polishing of dielectric materials. Urea was selected to dominate the growth and morphology during the calcination process. Thermogravimetry experiments were used to analyze the the decomposition behavior. Particle morphology and size were analyzed. Crystalline phase information and surface valence were used to compare the differences in surface physical and chemical properties of ceria by different synthesis process. The CeO2nanoparticles synthesized with urea were dispersed in water as slurry. The particle sizes of CeO2were measured by dynamic light scattering. The Zeta potential of CeO2dispersion were measured to show dispersing performance. The CeO2nanoparticles synthesized with urea condensation show good monodisperse properties. The material removal rate of silicon oxide and surface quality after chemical mechanical polishing were selected to evaluate the chemical mechanical polishing performance. The CeO2nanoparticles synthesized with urea condensation not only yielded better surface quality results than the commercial slurry but also showed a 153% (pH = 4) and 100% (pH = 10) increase in the material removal rate of silicon oxide compared to commercial.

The accumulation of soil organic carbon (SOC) and total nitrogen (TN) is easily accomplished by returning crop straw, which strongly affects the formation and pore structure of aggregates, especially in black soil. We returned maize straw at different rates (6,000, 9,000, 12,000 and 15,000 kg ha-1) for nine years to investigate its influence on the SOC and TN contents in the SOC fractions of aggregates by combining size and density fractionation. Their subsequent influences on pore morphology and size distribution characteristics were examined using X-ray micro-computed tomography scanning (μCT). The results showed that returning straw significantly increased the contents of C and N in the SOC fractions of aggregates, especially at the return rates of 12,000 and 15,000 kg ha-1, which in turn promoted aggregate formation and stability, and ultimately amended pore structure. The pore size >100 μm, porosity (>2 μm), and morphological characteristics (anisotropy, circularity, connectivity and FD) significantly increased, but the total number of pores significantly decreased (P<0.05). Our results indicated that the amendment of the pore morphology and size distribution of soil aggregates was primarily controlled by the higher contents of C and N in the density fractions of aggregates, rather than in the aggregate sizes. Furthermore, this pore network reconfiguration favored the storage of C and N simultaneously. The findings of this study offer valuable new insights into the relationships between C and N storage and the pore characteristics in soil aggregates under straw return.

The formidable challenge of membrane fouling by high-viscosity oils remains a primary impediment to the sustainable application of separation membranes in treating oil-contaminated wastewater. Consequently, there is an imperative for the development of oil-contaminated wastewater treatment membranes endowed with self-cleansing capabilities. The current review aims to delineate the landscape of self-cleansing membranes tailored for the treatment of oil-contaminated wastewater. Embarking from the foundational theories and benchmarks of self-cleansing, the self-cleansing functionalities were classified into active and passive modalities. We encapsulate the strides made in research, encompassing domains such as super-wettable surfaces, synchronously filtered self-cleansing, and post-filtration high-efficiency self-cleansing, while concurrently identifying extant constraints and prospective trajectories. By meticulously categorizing and dissecting self-cleansing functionalities, the aim of this work is delving into the fundamental tenets of self-cleansing within membranes intended for treating oil-contaminated wastewater, and furnishing guidance for the design and advancement of self-cleansing functionalities in oil-water separation membranes.

As an important optical component in laser system, silicon mirror surface is required to have micron-level flatness and subnanometer-level roughness. The research concentrates on how to improve roughness as far as possible while maintaining flatness of silicon mirror surface during chemical mechanical polishing (CMP) process. A polishing edge effect model is established to explain the reason of flatness deterioration, and a roughness theoretical model is set up to get the limit of perfect surface roughness. Based on the models above, a polishing device is designed to maintain the surface flatness, and the optimized polishing process parameters are obtained by orthogonal tests to get a near-perfect surface roughness. Finally the maintenance of flatness and the improvement of roughness can be achieved at the same time in one step of CMP process. This work can be a guide for silicon mirror manufacture to improve optical reflection performance significantly.

Rhizobial diversity is affected by interactions between soil features, fertilization strategy, and cropping system. However, interactions among the rhizobial community, chemical-organic manure fertilization, and plant production have not been well documented in Mollisols from long-term experiments. Aimed at maintaining and recovering the productivity of Chinese Mollisols, a long-term fertilization experiment had been carried out for 29 years under a wheat-maize-soybean rotation system, involving the application of recycled organic manure (ROM), chemical fertilizers (N, P, and/or K), or ROM plus N, P, and/or K. In the present study, the effects of different treatments were evaluated by determining soil physicochemical features, soybean production, and soybean rhizobial diversity. The results showed that application of ROM plus NPK maintained or increased soil fertility, which was accompanied by higher production and higher diversity of rhizobia, as compared with the other treatments. The negative association of Bradyrhizobium japonicumwith N fertilizer, positive association of B. diazoefficienswith soil pH, and alleviation of N-inhibition on the diversity of Bradyrhizobiumby the addition of ROM were recorded as new findings. Therefore, application of ROM or ROM plus NPK could be a feasible strategy for maintaining and recovering the fertility of Chinese Mollisols, whereas rhizobial diversity could be an indicator of soil fertility.

To clarify the chemical mechanical polishing (CMP) mechanism of Cu in aqueous hydrogen peroxide and glycine, we developed a ReaxFF reactive force field to describe the interaction between Cu, slurry (H2O, H2O2, and glycine), and the silica abrasive. Based on this force field, we used molecular dynamics simulations to illustrate the chemistry at the Cu/silica abrasive interface and Cu atom removal mechanism during the Cu CMP process. Our results indicate that H2O easily chemically adsorbs on the Cu surface, and H2O2can dissociate into hydroxyl radicals, forming Cu–OH. Besides, the OH-terminated silica surface can chemically interact with the Cu substrate, leading to the formation of Cu–OH on the Cu substrate. During the CMP process, Cu atoms on the substrate are effectively removed due to the mechanical sliding process-induced chemical reactions, including mainly three removal pathways: shear-induced glycine-adsorbed Cu atom removal process, shear-induced OH-adsorbed Cu atom removal process, and shear-induced Cu atom removal process due to the formation of interfacial Cu–O–Si bridge bonds. These results provide atomistic insights into the chemical reactions under mechanical effects in the Cu CMP process, thus helping the slurry design and process parameter optimization.

Marangoni drying is a highly concerned technology in the integrated circuit (IC) manufacturing, which removes the deionization (DI) water on the wafer surface in the wet cleaning process after chemical mechanical polishing (CMP). When the wafer is withdrawn from a DI water bath, Marangoni effect is induced by the organic vapor blown at the meniscus. It contributes to the backflow and stripping of the entrained water on the wafer and then achieves an ultraclean surface. Herein, the Marangoni drying performance is experimentally investigate using a self-developed drying device. Firstly, the visible water film on the wafer surface before and after Marangoni drying is observed. It indicates that Marangoni effect dramatically increases the critical withdrawal velocity where the visible water is formed. Further, the fluorescent particles are added in DI water, and the drying performance is characterized by counting the deposited particles using a fluorescent microscope. Such a method indirectly reflects the drying performance. The experimental results show that withdrawal velocity, organic vapor flux and blown angle exert significant impacts on the drying performance.

The study on the behaviour of decarburization, temperature increase, change of phosphorus and oxygen content of liquid steel during reblow process was presented in this paper. On the basis of traditional three-stage decarburization theory and thermal equilibrium theory, models for the variation of carbon content and temperature were established. Moreover, with application of data mining method, models for change of phosphorus and oxygen content were built based on large amount of production data and thermodynamic theory. By considering the variation of composition and temperature of molten steel, the reblow model was obtained and the software for reblow operation was developed with the combination of production technology. The test results indicated that the reblow rate (reblow more than once) dropped from 3.99 % to 0, and the average tap to tap time was reduced from 37.43 min to 36.35 min. It could provide an effective solution for medium-high carbon steel melting.

Cobalt (Co) with its low resistivity, excellent resistance to electro-migration with co-deposition property and void-free seamless fill ability, pledges to transform the landscape of integrated circuits in many areas, especially in logic contacts and interconnects. Chemical mechanical polishing (CMP), which utilizes the synergistic action of chemical corrosion and mechanical wear, has been recognized as the exclusive manufacturing approach to achieve global and local planarization of wafer surfaces. In this work, we proposed an innovative hydrogen peroxide (HP) polishing slurry, applying phthalic acid as the complexing agent and oleic acid as the corrosion inhibitor at pH 10. From the results of appropriate material removal/static etching rates as well as the smooth surface morphologies, phthalic acid and oleic acid are identified to be qualified in HP-based slurries for heterogeneous materials of Co interconnects. Moreover, the mechanisms of complexation and inhibition have been revealed by electrochemical analysis and X-ray photoelectron spectroscopy tests. It can be concluded that with the addition of complexing agent phthalic acid in HP-based slurries, the transformation of oxidization from low-valence compounds to high-valence was partially replaced by stronger complexing action, making the removal mechanism be attributed to the combined oxidization and complexation. When oleic acid is introduced, it could react with Co oxides to form a polymer protection layer adsorbing on Co films, achieving an inhibition effect to avoid Co excessive corrosion. Meanwhile, the oxidization of HP as well as the complexation of phthalic acid, combined with the protection of oleic acid play critical roles to maintain the appropriate removal rates and selection ratios.

Nanotribology has been given increasing attention by researchers in pursuing the nature of friction. In the present work, an approach that combines the supramolecular assembly and nanotribology is introduced. Herein, the nanotribological study was carried out on seven supramolecular template networks [namely, hydrogen bond induced tricarboxylic acids and van der Waals force induced hexaphenylbenzene (HPB) derivatives]. The template networks, as well as the host–guest assemblies of template molecules induced by different forces, were constructed on the highly oriented pyrolytic graphite (HOPG) surface and explicitly characterized using scanning tunneling microscopy (STM). Meanwhile, the nanotribological properties of the template networks were measured using atomic force microscopy (AFM). Together with the theoretical calculation using the density functional theory (DFT) method, it was revealed that the friction coefficients were positively correlated with the interaction strength. The frictional energy dissipation mainly derives from both the intermolecular interaction energy and the interaction energy between molecules and the substrate. The efforts not only help us gain insight into the competitive mechanisms of hydrogen bond and van der Waals force in supramolecular assembly but also shed light on the origin of friction and the relationship between the assembly structures and the nanotribological properties at the molecular level.

In the integrated circuits industry, 3D integration technology has been extensively studied. Through silicon via (TSV) technology is the core technology of the 3D integration. Chemical mechanical planarization (CMP) process, due to its high ability to achieve local and global planarization, is introduced into the traditional 1st back side via reveal (BVR) process during the back side thinning and flattening of TSV wafers. In this paper, CMP experiments were performed to study the selective removal of the back side TSV heterogeneous microstructure using alkaline slurry with hydrogen peroxide as oxidant. Atomic force microscope (AFM) measurements were used to evaluate the surface topography, and energy dispersive spectrometer (EDS) was used to characterize the surface chemistry. Scratch experiments were also conducted by AFM method to characterize the removal mechanism on the Cu surface during CMP. Based on the experimental results, the behaviors and mechanism of H2O2, BTA and pH value in different CMP slurries were discussed. The results show that a slurry contains 0.3 wt%-0.6 wt% H2O2, 15 mM of BTA and pH value of 10.5-11 is suitable to achieve a smooth polished surface. Findings in the research will have a guiding significance to the research of TSV back side CMP and BVR process.

Through silicon via (TSV) technology is widely used to achieve 3D integration of integrated circuits. Chemical mechanical planarization (CMP) is a mature technology to achieve both local and global planarization which can be applied in the traditional 1st back side via reveal (BVR) process during the back side thinning and flattening of TSV wafers. In this paper, the surface and subsurface micro-damage of the TSV heterogeneous microstructure after back side CMP process was observed and characterized by cross-sectional transmission electron microscope (TEM) measurements, microscopic high resolution Raman spectra and I-V curves were also measured. As the results, CMP introduces micro-damage to surface and subsurface of Cu (local defects), of interface between Cu and barrier material (bimetallic corrosion), of Si (amorphous layers) and of insulation material (leakage current). The results illustrate that CMP induced amorphous Si layer shows barrier property, CMP changes the barrier property of Ti/TiN little, slurry formulation changes the insulation property of polished TEOS much, the addition of 5 mM BTA to CMP slurry and the controlling of pH[?]10.5 can help to protect the back side surface of TSV wafers during CMP and to reduce the surface and subsurface damage of the back side metal structures. The conclusions in the research will guide the further research of TSV back side CMP and BVR process.

Ru as a novel barrier/liner material for Cu interconnects, has gained application in the sub-10 nm technology node. In this paper, methods to polish patterned wafer with Ru/Ta/TaN tri-layers as liner/barrier have been proposed. Effects of pattern geometry and CMP variables (such as polishing down pressure and oxidant content) on polishing uniformity were fully investigated. Apart from this, interfacial defects after barrier polishing were comprehensive characterized by atomic force microscopy and transmission electron microscopy methods. Results show that hydrogen peroxide (H2O2) is effective in the mutual material removal of Cu/Ru/Ta/TaN/BD1 heterogeneous materials. Good surface quality could be obtained by using proper CMP process, with Cu dishing of 604.1 A for the 100/100 um array.

The Marangoni effect induced by organic vapor has drawn considerable attention in integrated circuit manufacturing for eliminating watermark defects encountered in the wafer drying process. Accordingly, a vertical rotational Marangoni (VRM) dryer based on the combination of the Marangoni effect and centrifugal force is proposed and developed. In particular, the hydrodynamic behavior of the VRM dryer is investigated to reveal the mechanism of ultraclean drying. A three-dimensional model of the VRM dryer is proposed, and the flow field of the water film and distribution of organic species are adequately analyzed. The results show that the rotational velocity and wettability significantly affect the coverage uniformity of the water film, and the exposure region at the three-contact line leads to the watermark. Furthermore, the coupling behavior of the Marangoni effect and centrifugal force is revealed. A higher rotational velocity leads to worse integrity of the water film covering, and thus, fainter Marangoni effect. Polishing and cleaning experiments are conducted to verify the effectiveness of theoretical analysis. The results indicate that the optimized rotational velocity for the hydrophilic surface is higher than that of the hydrophobic surface. The mechanism analysis of wafer drying based on the VRM drying technology provides effective guidance for ultraclean surface manufacturing during the cleaning process.

Cobalt (Co) and its low resistivity, superior adhesion property, and void-free seamless fill ability, pledge to transform the landscape of integrated circuits in many areas, especially in interconnects and logic contacts. Chemical mechanical polishing (CMP), which can realize local and global planarization, has been recognized as one of the indispensable manufacturing approaches for the fabrication of multilevel metal interconnection structures. The present work introduces diethanolamine (DEA) into our alkaline glycine-based slurries for Co CMP process. The action mechanism of DEA on Co CMP process in glycine-based slurries at pH 8.1 has been clearly revealed by various approaches, including polishing and static etching experiments, X-ray photoelectron spectroscopy survey, electrochemical analysis, as well as adsorption isotherm calculation. At low concentrations, DEA could be able to accelerate the polishing process via its auxiliary complexing effect, obtaining higher removal rates and larger corrosion current densities. Some pitting corrosion could appear on Co surfaces due to the production of Co-glycine complex as well as the auxiliary complexing process, making rougher surface qualities. On the other hand, when the DEA concentration increased to a certain level, it could play a role of corrosion inhibitor, protecting Co surfaces by forming a stable passive layer and moderating material removal rates, removal selectivity, and surface roughness.

We describe a direct atomic layer deposition method to grow lubricant tungsten disulfide (WS2) films. The WS2films were deposited on a Si (100) substrate and a zinc sulfide (ZnS) film coated the Si (100) substrate using tungsten hexacarbonyl and hydrogen sulfide as precursors. The ZnS film served as an intermediate layer to facilitate the nucleation and growth of the WS2films. The thickness of the WS2films was measured via scanning electron microscope, the microstructure was probed with an X-ray diffractometer and a transmission electron microscope. The friction coefficient was measured with a ball-on-disk tester under dry nitrogen. The results reveal that the WS2films deposited on both substrates are ~175 nm and have (002) and (101) crystal orientations. The WS2film deposited on the ZnS coated Si substrate exhibits a stronger (002) orientation and a denser crystal structure than that deposited on the Si substrate. The WS2films on both substrates have low friction coefficients. However, due to the stronger (002) orientation and denser crystal structure, the friction coefficient of the WS2film deposited on ZnS coated Si substrate is smaller with longer wear life.

Galvanic corrosion of Cu is a critical issue during the chemical mechanical polishing (CMP) process of barrier layer, especially when KIO4 is used as the oxidant in the polishing slurry. This paper focuses on the investigation of galvanic corrosion inhibitors (BTA and 1, 2, 4-triazole) for Cu/Ru couple in the KIO4-based solutions. The galvanic corrosion current of Cu was directly measured, and the corrosion inhibition efficiencies (CIE) were calculated. Results show that both BTA and 1, 2, 4-triazole are effective galvanic corrosion inhibitors of Cu. The CIE of 5 mM BTA and 2 mM 1, 2, 4-triazole is up to 69.4 and 59.7, respectively. On this basis, the corrosion inhibition mechanism was proposed. BTA forms a complete and tight three-dimensional multilayer structure on Cu when the concentration is over 0.5 mM. With regard to 1, 2, 4-triazole, the protective film on Cu is two-dimensional, and excessive dosage of 1, 2, 4-triazole will reduce the stability of the surface film, as well as the corrosion inhibition efficiency of Cu.

Cleaning processes draw considerable attention in integrated circuit manufacturing because of the rapid development of technology nodes. Bare silicon wafer cleaning after chemical mechanical polishing (CMP) is one of the most difficult processes used to meet the extremely strict industrial requirements. Herein, the silicon wafer cleaning mechanism is studied in detail. The effects of megasonic and brush cleaning on nanoparticle removal are both analysed through experiments and simulations. The experimental results show that chemical concentration, megasonic vibration power, and brush clamp gap all significantly affect the cleaning performance, and that excessive megasonic power reduces the cleaning performance because more defects are introduced. A model of megasonic nozzle trajectory is also proposed, and optimized parameters, especially the relative velocity between the wafer rotation and nozzle movement, are critical to removing nanoparticles effectively. Furthermore, analysis of combining megasonic and brush cleaning shows that including megasonic cleaning improves the wafer cleaning performance by several orders of magnitude. Based on the optimized cleaning conditions, an ultraclean wafer surface is achieved after CMP.

Chemical mechanical polishing (CMP) of GaN(0001) with a H2O2-SiO2-based slurry is investigated in this paper. The result shows that an atomically flat surface with a roughness of 0.065 nm is obtained after polishing. Compared with a SiO2-based slurry, the H2O2-SiO2-based slurry can realize a higher material removal rate (MRR) and a better surface quality with less scratches. The pH value mainly affects the mean particle size of SiO2 and the chemical environment of the corrosion reaction with H2O2, resulting in different MRRs. An off-site auxiliary polishing method is employed along with the H2O2-SiO2-based polishing system using ultraviolet light to shine the outlet of slurry in order to catalyze the production of substance for oxidation, and it is proved to be efficient by improving the MRR to 103 nm/h. Physical and mathematic removal models are proposed to describe the removal mechanism of GaN CMP.

In a nanoscale friction test, wear of an atomic force microscope (AFM) tip is inevitable. The shape of the worn tip influences the friction force measured. In order to eliminate the influence, nanowear pretreatment should be conducted for the AFM tip. In our study, pretreatment of three kinds of tips, i.e. Si3N4tip, Si tip and silica colloidal tip, was performed using AFM. The results show that the shape of the tips changes with the increase of sliding distance, which leads to the variety of friction force. Whereas, when the tip gets blunt, the shape of tip tends to become stable and the friction force becomes stable correspondingly. To a certain degree, it reveals that the pretreated tips can be applied to study the friction force of samples.

Nanoparticle movement near a surface is greatly influenced by electrostatic and Van der Waals forces between the particle and the surface, as well as by Brownian motion. In this paper, several precise equations are derived to describe the Van der Waals and electrostatic forces between a particle and a surface when the particle is removed from the surface. These include an equation for particle displacement under the electrostatic force, and a numerical calculation for particle displacement under the Van der Waals force. Finally, a kinematic model is constructed to describe the particle distribution under the effects of the electrostatic and Van der Waals forces, as well as the particle’s Brownian motion. The results show that increasing the multiply of the particle and surface zeta potential values and decreasing the ionic strength of the detergent can prevent a particle from redepositing onto a surface.

Soil water, organic C, and N management practices exert strong influences on winter wheat (Triticum aestivumL.) yield and soil properties under dryland farming conditions. Here, a 9‐yr field experiment was conducted in northwestern China using treatments that included nine factorial combinations of three cultivation practices, conventional cultivation (CC), straw mulching (SM), and supplementary irrigation (SI), and three N application rates (0, 120, and 240 kg N ha−1). Relative yield gradually declined under CC and SM with N, yet remained steady under SI. Without N, yield decreased by 50 to 60%. Soil organic carbon (SOC), labile organic carbon (LOC), total nitrogen (TN), and available potassium (AK) in the 0 to 20 cm (upper) soil layer were significantly increased by SM but were unaffected by SI treatments. After wheat harvest, N application increased SOC, LOC, and TN in the upper soil layer by an average of 4.81, 20.70, and 7.61%, respectively, and decreased AK by 6.12%. The cultivation practice and N fertilizer effects on soil properties were more pronounced in upper than deeper layer (20–40 cm). At soil depths of 0 to 100 cm, nitrate accumulation under N240exceeded 69.27% of the critical environmental risk value. Thus, SI + N120achieved a high and stable wheat yield, and SM + N120increased soil fertility. However, the two combinations applied over 9 yr did not meet both high soil fertility and high productivity needs. Additionally, cultivation practices with high N fertilizer are not sustainable soil management techniques in dryland regions.

Adhesion is a big concern for the design of Si-based microelectromechanical devices. A ZnO film with nanoscale surface roughness is a promising candidate to decrease adhesion as the protective coating. In this study, the adhesion force of ZnO films prepared by atomic layer deposition (ALD) on a Si (100) substrate was studied. The root-mean-square (RMS) roughness of the ZnO films was in the range of 0.7–4.28 nm, and the contact angle of water was in the range of 85–88°. The adhesion force was measured by atomic force microscopy (AFM) at both low (12%) and high (60%) relative humidities. The results show that the adhesion force decreases as the surface roughness increases. A low adhesion force at high RMS roughness is attributed to the large asperities on the film, and a large adhesion force at high humidity is attributed to the large capillary force. The experimental adhesion force was compared to the force calculated using the Rabinovich model. Although the theoretical value underestimates the experimental value, the proportion of the two components of the adhesion force is clearly shown. At the low humidity, the van der Waals force component differs not greatly with the capillary force component, while at the high humidity, the capillary force component becomes dominant.

For several decades, chemical mechanical polishing (CMP) has been the most widely used planarization method in integrated circuits manufacturing. The final polishing results are affected by many factors related to the carrier structure, the polishing pad, the slurry, and the process parameters. As both chemical and mechanical actions affect the effectiveness of CMP, and these actions are themselves affected by many factors, the CMP mechanism is complex and has been a hot research area for many years. This review provides a basic description of the development, challenges, and key technologies associated with CMP. We summarize theoretical CMP models from the perspectives of kinematics, empirical, its mechanism (from the viewpoint of the atomic scale, particle scale, and wafer scale), and its chemical-mechanical synergy. Experimental approaches to the CMP mechanism of material removal and planarization are further discussed from the viewpoint of the particle wear effect, chemical-mechanical synergy, and wafer-pad interfacial interaction.

Continued reduction in feature dimension in integrated circuits demands high degree of flatness after chemical mechanical polishing. Here we report using new yttrium oxide (Y2O3) nanosheets as slurry abrasives for chemical-mechanical planarization (CMP) of copper. Results showed that the global planarization was improved by 30% using a slurry containing Y2O3nanosheets in comparison with a standard industrial slurry. During CMP, the two-dimensional square shaped Y2O3nanosheet is believed to induce the low friction, the better rheological performance, and the laminar flow leading to the decrease in the within-wafer-non-uniformity, surface roughness, as well as dishing. The application of the two-dimensional nanosheets as abrasive in CMP would increase the manufacturing yield of integrated circuits.

During the ultra large scale integration (ULSI) process, the surface roughness of the polished silicon wafer plays an important role in the quality and rate of production of devices. In this work, the effects of oxidizer, surfactant, polyurethane pad and slurry additives on the surface roughness and topography of chemical-mechanical planarization (CMP) for silicon have been investigated. A standard atomic force microscopy (AFM) test method for the atomic scale smooth surface was proposed and used to measure the polished silicon surfaces. Finally, compared with the theoretical calculated Ravalue of 0.0276 nm, a near-perfect silicon surface with the surface roughness at an atomic scale (0.5 Å) was achieved based on an optimized CMP process.

A finite element analysis (FEA) model is developed for the chemical-mechanical polishing (CMP) process on the basis of a 12-in five-zone polishing head. The proposed FEA model shows that the contact stress non-uniformity is less dependent on the material property of the membrane and the geometry of the retaining ring. The larger the elastic modulus of the pad, the larger contact stress non-uniformity of the wafer. The applied loads on retaining ring and zone of the polishing head significantly affect the contact stress distribution. The stress adjustment ability of a zone depends on its position. In particular, the inner-side zone has a high stress adjustment ability, whereas the outer-side zone has a low stress adjustment ability. The predicted results by the model are shown to be consistent with the experimental data. Analysis results have revealed some insights regarding the performance of the multi-zone CMP.

An ultrathin layer is investigated for its potential application of replacing conventional diffusion barriers and promoting interface adhesion for nanoelectric circuits with porous ultralow dielectrics. The porous ultralow dielectric (k≈ 2.5) substrate is silanized by 3-aminopropyltrimethoxysilane (APTMS) to form the nanoadhesive layer by performing oxygen plasma modification and tailoring the silanization conditions appropriately. The high primary amine content is obtained in favor of strong interaction between amino groups and copper. And the results of leakage current measurements of metal-oxide-semiconductor capacitor structure demonstrate that the aminosilanization nanoadhesive layer can block copper diffusion effectively and guarantee the performance of devices. Furthermore, the results of four-point bending tests indicate that the nanoadhesive layer with monolayer structure can provide the satisfactory interface toughness up to 6.7 ± 0.5 J/m2for Cu/ultralow-kinterface. Additionally, an annealing-enhanced interface toughness effect occurs because of the formation of Cu–N bonding and siloxane bridges below 500 °C. However, the interface is weakened on account of the oxidization of amines and copper as well as the breaking of Cu–N bonding above 500 °C. It is also found that APTMS nanoadhesive layer with multilayer structure provides relatively low interface toughness compared with monolayer structure, which is mainly correlated to the breaking of interlayer hydrogen bonding.

In China, wheat (Triticum aestivumL.) grown on Zn‐deficient calcareous soils often fails to meet the dietary needs of local populations. The effectiveness of Zn application to a potentially Zn‐deficient calcareous soil was measured using two winter wheat cultivars and five Zn fertilizer rates (0, 7.5, 15, 30, 45 kg Zn ha−1). The results showed that Zn fertilizer increased grain Zn concentration in 2008–2009 by 11 to 33%; however, grain Zn concentrations were still insufficient for human dietary requirements. The apparent Zn utilization efficiency was between 0.14 and 0.98%. Within 1 wk of fertilizer Zn application, Zn weakly bound to organic matter (Wbo‐Zn) increased by amounts equivalent to 63.4 to 84.0% of the fertilizer Zn application. Carbonate‐bound Zn increased by amounts equivalent to 6.5 to 10.3% of the fertilizer Zn. The Wbo‐Zn fraction decreased gradually with time, whereas mineral‐bound Zn increased. Calculations indicated that 62.0 to 78.1% of the fertilizer Zn was mineral bound after 639 d. Diethyltriamine pentaacetic acid extractable Zn concentrations increased by 267 to 529% immediately after Zn fertilization but then decreased. In conclusion, available soil Zn concentrations increased quickly after Zn fertilizer application to a potentially Zn‐deficient calcareous soil; however, the available Zn fractions were soon converted to mineral‐bound forms that were unavailable for plant uptake.

Copper chemical mechanical planarization (CMP) was conducted in the H2O2 based slurry containing glycine and BTA, with/without the nonionic surfactant hydroxyethyl cellulose (HEC). The result showed that with the addition of HEC, the material removal rate increased obviously, and the generation of corrosion pits on the polished surface was reduced. Surface with roughness of 0.8 nm can be obtained when the concentration of HEC is 0.01%. It shows that there is a potential for HEC in the commercial application. In order to investigate the role of HEC in copper CMP, the static corrosion rates of copper in the slurry with/without glycine/BTA were studied. Viscosity measurement and electrochemical test was introduced in this study. XPS was also used to analyze the effect of HEC during the Cu CMP. Finally, the role of HEC in the chemical mechanical planarization of copper was discussed.

A 2-year field experiment was conducted (i) to study the effect of combined P and Zn fertilization on the Zn nutritional quality of wheat grown on potentially Zn-deficient calcareous soil and (ii) to identify which soil Zn fraction had the greatest effect on grain Zn concentration. Results showed that Zn fertilization increased grain Zn concentrations by 13 in 2006–2007 and 15 in 2007–2008. However, the application of 200 kg P2O5ha−1combined with Zn fertilizer reduced grain Zn concentrations by 38 in 2006–2007 and 17 in 2007–2008 compared with the control (no fertilizer treatment). The phytic acid (PA) concentration and the PA:Zn molar ratio in wheat grain increased as P fertilizer application rate increased, regardless of the Zn fertilizer application rate. Zinc fertilization alone increased diethyltriaminepentaacetic acid–Zn by 220 in 2006–2007 and 470 in 2007–2008 compared with the no Zn fertilizer treatment. The combined application of P and Zn also increased diethyltriaminepentaacetic acid–Zn and loose organic matter–bound Zn, but the increase became smaller as the P fertilizer application rate increased. In conclusion, P fertilizer application rates to the potentially Zn-deficient calcareous soil used in this study should be less than 100 kg P2O5ha−1to ensure the efficacy of the Zn fertilizer. Among the soil Zn fractions in this study, loose organic matter–bound Zn had the greatest correlation with grain Zn concentration.

Based on the corrosion-wear theory, a mathematical material removal model incorporating both chemical and mechanical effects during chemical-mechanical planarization (CMP) is proposed in this paper. The model not only quantifies the chemical-mechanical synergy, but also isolates each component's contribution to the material removal rate. Synergetic effects on material removal rate are simulated according to the corrosion-wear map. Furthermore, the influences of process parameters and particle size are analyzed. Although the experimental verification has yet to follow, the model predictions are in good agreement with the existing models and published experimental results. In addition, the model will provide an approach for assessing dominant factors in material removal rate during CMP.

In this paper, a novel in-situ interfacial fluid pressure measurement system is developed for the practical chemical mechanical polishing (CMP) equipment, in which the pressure sensors are equidistantly embedded in the platen along the radial direction and sweep beneath the wafer surface during CMP. Interfacial fluid pressure mapping is realized for standard 12'' blanket wafers at the down pressure of 0.5 [?] 2.0 psi. The fluid pressure profiles from the leading edge to the trailing edge and the pressure contour maps of the fluid film across the whole wafer surface are constructed and displayed. Results reveal a large positive pressure region located near the wafer trailing edge and a small negative pressure region located near the leading edge, which is quite different from the negative dominated results of previous studies. The fluid pressure can support 15% [?] 30% of the applied pressure. The down pressure has great effect on the fluid pressure due to the wafer's bend under the applied load. When the down pressure increases, the positive pressure region expands and slightly shifts toward the outer of the pad while the negative pressure region shrinks.

The performance of sodium dodecyl sulfate (SDS), an anion surfactant, in a slurry with glycine and hydrogen peroxide for copper-chemical mechanical polishing (Cu-CMP) was studied. The wettability and surface tension of the slurry for copper and the zeta potential of were examined. The influence of SDS on the static corrosion, material removal rate, and the surface roughness was studied. The results showed that SDS improved Cu-CMP performance by changing the physical characteristics of the slurry and protecting the copper surface from corrosion and scratches. A surface with the lowest amount of scratches and corrosion after polishing was obtained when concentration of the SDS surfactant was in the glycine- solution. The mechanism of action between the SDS and copper surface was investigated by electrochemical polarization and X-ray photoelectron spectroscopy. Finally, a physical model was developed to describe the interactions between particles, the copper surface, and SDS in the slurry.

Micro-assembling Teflon/Si3N4multilayer film was developed by ion beam alternating sputtering Teflon and Si3N4ceramic targets. The structural, mechanical and microtribological properties were studied by PHI-5300, FTIR, XRD and atomic force and friction force microscope (AFM/FFM). The results show that the multilayer consists of Si3N4component and crystalline Teflon. The hardness of the multilayer is less than that of Si3N4; but the toughness of Teflon/Si3N4is greatly improved. The friction coefficient of Teflon/Si3N4multilayer is lower than that of Si3N4film, and the wear resistance of Teflon/Si3N4multilayer is much greater than that of Teflon film. The friction force of Teflon/Si3N4film is linear with the load in nanoscale. The worn track will be formed in Teflon and Teflon/Si3N4film when the load is greater than 70 nN.

Wafer drying induced by Marangoni effect is crucial to achieving an ultraclean surface in integrated circuit manufacturing. According to the previous opinions, the entrained water film on wafer surface was stripped by Marangoni effect, and thus the watermark defect induced by evaporation was inhibited. However, the influence of particle removal induced by Marangoni effect on the ultraclean surface preparation is lack of adequate understanding. The present work implements an experimental and numerical investigation of wafer cleaning behavior engendered by Marangoni effect during the wafer withdrawn process. The impacts of critical process parameters and substrate properties on the particle removal efficiency are systematically studied. The results show that Marangoni effect has better cleaning performance on the glass substrate compared with that of silicon and copper. The numerical simulation indicates that the Marangoni effect is more dramatic on glass substrate owing to the better wettability. Furthermore, the stress analysis reveals the adsorption force of fluorescent particle on the copper surface is stronger than that of silicon and glass. Therefore, particle cleaning on the copper surface is much more difficult. The investigation of cleaning performance driven by the Marangoni effect will contribute to a comprehensive understanding of the mechanism of ultraclean surface preparation.

In this study, a method to improve the chemical mechanical polishing (CMP) performance of ceria as abrasive particles was proposed. Surface doping of ceria nanoparticles was realized by incipient impregnation method, in order to improve its valance change properties (Ce3+/Ce4+). This study presents detailed characterization of the lanthanide-doped CeO2 by both experimental methods and density functional theory (DFT) calculation. The dispersion stability of the doped ceria nanoparticles in CMP slurries are investigated. Results show that the doped CeO2 nanoparticles exhibit more oxygen vacancies and higher content of Ce3+ compared with the pristine CeO2. Good dispersion stability of the doped CeO2 nanoparticles could be achieved by adding dispersants in the CMP slurries.

In this study, a method to improve the chemical mechanical polishing (CMP) performance of ceria as abrasive particles was proposed. Surface doping of ceria nanoparticles was realized by incipient impregnation method, in order to improve its valance change properties (Ce3+/Ce4+). This study presents detailed characterization of the lanthanide-doped CeO2by both experimental methods and density functional theory (DFT) calculation. The dispersion stability of the doped ceria nanoparticles in CMP slurries are investigated. Results show that the doped CeO2nanoparticles exhibit more oxygen vacancies and higher content of Ce3+compared with the pristine CeO2. Good dispersion stability of the doped CeO2nanoparticles could be achieved by adding dispersants in the CMP slurries.

Wafer drying induced by Marangoni effect is crucial to achieving an ultraclean surface in integrated circuit manufacturing. According to the previous opinions, the entrained water film on wafer surface was stripped by Marangoni effect, and thus the watermark defect induced by evaporation was inhibited. However, the influence of particle removal induced by Marangoni effect on the ultraclean surface preparation is lack of adequate understanding. The present work implements an experimental and numerical investigation of wafer cleaning behavior engendered by Marangoni effect during the wafer withdrawn process. The impacts of critical process parameters and substrate properties on the particle removal efficiency are systematically studied. The results show that Marangoni effect has better cleaning performance on the glass substrate compared with that of silicon and copper. The numerical simulation indicates that the Marangoni effect is more dramatic on glass substrate owing to the better wettability. Furthermore, the stress analysis reveals the adsorption force of fluorescent particle on the copper surface is stronger than that of silicon and glass. Therefore, particle cleaning on the copper surface is much more difficult. The investigation of cleaning performance driven by the Marangoni effect will contribute to a comprehensive understanding of the mechanism of ultraclean surface preparation.

In this paper, we discuss the frictional behaviour of molecular thin films on a mica surface at a nanometre scale. Carbon 60 (C60)‐based macromolecules were synthesized experimentally. Analytical techniques such as Fourier transform infrared spectroscopy, UV–VIS spectroscopy and gel permeation chromatography were used to analyze the synthesized product. The Langmuir–Blodgett technique was used in making the macromolecules in the thin film on the mica surface. Atomic force microscopy and friction force microscopy were used for surface characterization. The properties, novel structures and their effects on frictional properties are discussed based on experiment results. It is found that the molecular thin films can be transferred onto the mica surface. These thin films possess significant tribological properties. Copyright © 2001 John Wiley & Sons, Ltd.

In this paper, we discuss the frictional behaviour of molecular thin films on a mica surface at a nanometre scale. Carbon 60 (C60)-based macromolecules were synthesized experimentally. Analytical techniques such as Fourier transform infrared spectroscopy, UV–VIS spectroscopy and gel permeation chromatography were used to analyze the synthesized product. The Langmuir–Blodgett technique was used in making the macromolecules in the thin film on the mica surface. Atomic force microscopy and friction force microscopy were used for surface characterization. The properties, novel structures and their effects on frictional properties are discussed based on experiment results. It is found that the molecular thin films can be transferred onto the mica surface. These thin films possess significant tribological properties. Copyright © 2001 John Wiley & Sons, Ltd.

Marangoni drying is a highly concerned technology in the integrated circuit (IC) manufacturing, which removes the deionization (DI) water on the wafer surface in the wet cleaning process after chemical mechanical polishing (CMP). When the wafer is withdrawn from a DI water bath, Marangoni effect is induced by the organic vapor blown at the meniscus. It contributes to the backflow and stripping of the entrained water on the wafer and then achieves an ultraclean surface. Herein, the Marangoni drying performance is experimentally investigate using a self-developed drying device. Firstly, the visible water film on the wafer surface before and after Marangoni drying is observed. It indicates that Marangoni effect dramatically increases the critical withdrawal velocity where the visible water is formed. Further, the fluorescent particles are added in DI water, and the drying performance is characterized by counting the deposited particles using a fluorescent microscope. Such a method indirectly reflects the drying performance. The experimental results show that withdrawal velocity, organic vapor flux and blown angle exert significant impacts on the drying performance.

In the integrated circuits industry, 3D integration technology has been extensively studied. Through silicon via (TSV) technology is the core technology of the 3D integration. Chemical mechanical planarization (CMP) process, due to its high ability to achieve local and global planarization, is introduced into the traditional 1stback side via reveal (BVR) process during the back side thinning and flattening of TSV wafers. In this paper, CMP experiments were performed to study the selective removal of the back side TSV heterogeneous microstructure using alkaline slurry with hydrogen peroxide as oxidant. Atomic force microscope (AFM) measurements were used to evaluate the surface topography, and energy dispersive spectrometer (EDS) was used to characterize the surface chemistry. Scratch experiments were also conducted by AFM method to characterize the removal mechanism on the Cu surface during CMP. Based on the experimental results, the behaviors and mechanism of H2O2, BTA and pH value in different CMP slurries were discussed. The results show that a slurry contains 0.3 wt%–0.6 wt% H2O2, 15 mM of BTA and pH value of 10.5–11 is suitable to achieve a smooth polished surface. Findings in the research will have a guiding significance to the research of TSV back side CMP and BVR process.

Ru as a novel barrier/liner material for Cu interconnects, has gained application in the sub-10 nm technology node. In this paper, methods to polish patterned wafer with Ru/Ta/TaN tri-layers as liner/barrier have been proposed. Effects of pattern geometry and CMP variables (such as polishing down pressure and oxidant content) on polishing uniformity were fully investigated. Apart from this, interfacial defects after barrier polishing were comprehensive characterized by atomic force microscopy and transmission electron microscopy methods. Results show that hydrogen peroxide (H2O2) is effective in the mutual material removal of Cu/Ru/Ta/TaN/BD1 heterogeneous materials. Good surface quality could be obtained by using proper CMP process, with Cu dishing of 604.1 Å for the 100/100 μm array.

Through silicon via (TSV) technology is widely used to achieve 3D integration of integrated circuits. Chemical mechanical planarization (CMP) is a mature technology to achieve both local and global planarization which can be applied in the traditional 1stback side via reveal (BVR) process during the back side thinning and flattening of TSV wafers. In this paper, the surface and subsurface micro-damage of the TSV heterogeneous microstructure after back side CMP process was observed and characterized by cross-sectional transmission electron microscope (TEM) measurements, microscopic high resolution Raman spectra and I-V curves were also measured. As the results, CMP introduces micro-damage to surface and subsurface of Cu (local defects), of interface between Cu and barrier material (bimetallic corrosion), of Si (amorphous layers) and of insulation material (leakage current). The results illustrate that CMP induced amorphous Si layer shows barrier property, CMP changes the barrier property of Ti/TiN little, slurry formulation changes the insulation property of polished TEOS much, the addition of 5 mM BTA to CMP slurry and the controlling of pH≈10.5 can help to protect the back side surface of TSV wafers during CMP and to reduce the surface and subsurface damage of the back side metal structures. The conclusions in the research will guide the further research of TSV back side CMP and BVR process.

Galvanic corrosion of Cu is a critical issue during the chemical mechanical polishing (CMP) process of barrier layer, especially when KIO4is used as the oxidant in the polishing slurry. This paper focuses on the investigation of galvanic corrosion inhibitors (BTA and 1, 2, 4-triazole) for Cu/Ru couple in the KIO4-based solutions. The galvanic corrosion current of Cu was directly measured, and the corrosion inhibition efficiencies (CIE) were calculated. Results show that both BTA and 1, 2, 4-triazole are effective galvanic corrosion inhibitors of Cu. The CIEof 5 mM BTA and 2 mM 1, 2, 4-triazole is up to 69.4 and 59.7, respectively. On this basis, the corrosion inhibition mechanism was proposed. BTA forms a complete and tight three-dimensional multilayer structure on Cu when the concentration is over 0.5 mM. With regard to 1, 2, 4-triazole, the protective film on Cu is two-dimensional, and excessive dosage of 1, 2, 4-triazole will reduce the stability of the surface film, as well as the corrosion inhibition efficiency of Cu.