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1.
Chemical mechanical polishing (CMP) processes are widely used in the semiconductor industry and are conventionally carried out using abrasive slurry and a polishing pad. In an alternative procedure, called ‘slurry free CMP’, the abrasive particles are embedded in the pad material (‘fixed abrasives’). A microreplicated resin layer of pyramids filled with the abrasives is placed on top of a rigid polycarbonate layer and a resilient foam sublayer. Instead of slurry, only DI-water or a basic solution is applied. Drying in of the slurry and glazing of the pad is not possible and pad conditioning is not required. Experiments were carried out for slurry free CMP to optimize the with-in-wafer non-uniformity (WIW-NU), removal rate and planarization of oxide ILD. Results of this optimization are compared with our best slurry process. It is shown that the fixed abrasives process is superior to the slurry process with regard to planarization: the rate of planarization is almost three times faster for the slurry free process. This enables further process optimization, such as the use of a thinner pre-CMP oxide layer. Besides higher planarization rates, better with-in-die non-uniformity (WID-NU) can be obtained by adjusting the subpad construction of these ‘slurry free’ pads. The flexibility of the pad construction makes it possible to optimize the WID-NU and WIW-NU. Stiffer pads give lower WID-NU, but for the stiffest pad the WIW-NU will slightly increase. However, compared to the slurry process both WID-NU and WIW-NU are better. 相似文献
2.
In this research, we conducted a series of experiments to investigate the mechanisms of chemical mechanical polishing (CMP)
of silicon. Experimental approaches include tribological tests of frictional and lubricating behavior, chemical analysis,
and surface characterization. Specifically, the effects of pH in slurry, surface roughness of wafers, and nano-particle size
on removal rate were studied. A transmission electron microscope (TEM), a scanning electron microscope (SEM), and x-ray characterization
tools were used to study the change of surface structure and chemistry. Experimental results indicate that the removal rate
and planarization are dominated by the surface chemistry. 相似文献
3.
The effect of mechanical process parameters such as down force and rotation speed on friction behavior and material removal rate (MRR) was investigated during chemical mechanical polishing (CMP) of sapphire substrate. It was found that the increase in both rotation speed and down force can enhance the MRR and friction force almost linearly depends on the down force and rotation speed. The coefficient of friction (COF) decreases with increasing rotation speed under a fixed down force but keeps constant regardless of variation in down force under a fixed rotation speed. Moreover, the relationship between friction force and MRR was obtained. MRR was proportional to friction force with increasing down force whereas converse proportional to that with increasing the rotation speed. In addition, MRR data are fitted to the Preston equation in the sapphire CMP. 相似文献
4.
It is well known that within wafer non-uniformity (WIWNU), due to the variation in material, removal rate (MRR) in the whole
wafer plays an important role in determining the quality of a wafer planarized by CMP. Various material removal models also
suggest that the MRR is strongly influenced by the interface pressure. In the present work, an analytical expression for pressure
distribution at the wafer and pad interface is developed. It is observed that depending on the wafer curvature and polishing
conditions, the interface pressure may exhibit significant variation. The analytical model predictions are first verified
against finite element method (FEM) simulations. The predicted analytical pressure profiles are then utilized in Preston's
equation to estimate the MRR, and these MRR predictions are also compared to experimental observations. The analytical results
suggest, that for a specified wafer curvature there exists a certain polishing condition (and vice versa) that will enable
holding the WIWNU within a specified tolerance band. The proposed model facilitates the design space exploration for such
optimal polishing conditions. 相似文献
5.
Ceria-based high selectivity slurry (HSS), which shows high polishing selectivity of silicon oxide to silicon nitride, was applied to the shallow trench isolation (STI) chemical mechanical planarization (CMP) process for giga-bit scale memory fabrication. While the wafer-to-wafer non-uniformity (WTWNU) and within-wafer non-uniformity (WIWNU) are superior to conventional silica-based slurry, the level of slurry induced scratches is too high for the ceria-based slurry to be used in present CMP processes. By optimizing the CMP process and filtering method, however, the number and depth of these scratches were reduced considerably to the level where the yield of gate oxide was sufficient to meet the requirement of manufacturing. In this paper, the authors discussed the possible causes of scratches when using ceria-based slurry and how these scratches affect to lower the breakdown yield of gate oxides. In addition, the authors investigated the relationship between within wafer non-uniformity and cell threshold voltage ( Vt) variation and probe test 1 (PT1) yield variation. 相似文献
6.
Effect of abrasive particle concentration on material removal rate (MRR), MRR per particle and the surface quality in the preliminary chemical mechanical polishing (CMP) of rough glass substrate was investigated. Experimental results showed that the MRR increases linearly with the increase of abrasive concentration and reaches to the maximum when the abrasive concentration is 20 wt.%, and then tends to be stable. When the abrasive concentration increases from 2 to 5 wt.%, the MRR per particle increases greatly and reaches a peak. Then the MRR per particle decreases almost linearly with the increase of the abrasive concentration. The root mean squares (RMS) roughness almost decreases with increasing particle concentration. In addition, in situ coefficient of friction (COF) was also conducted during the polishing process and the zeta potentials of abrasive particles in slurry with different solid concentration were also characterized. Results show that COF value is not related to zeta potential but be sensitive to glass surface conditions in terms of rough peaks in preliminary polishing of glass substrate. 相似文献
7.
The key component of ferroelectric random access memory (FeRAM) is a capacitor including a ferroelectric thin film and electrode materials. Platinum is one of the suitable metals which meet requirements such as low resistivity, high thermal stability, and good oxygen resistance. Generally, the ferroelectric and the electrode materials were patterned by a plasma etching process. The application possibility of chemical mechanical polishing (CMP) processes to the patterning of ferroelectric thin film instead of plasma etching was investigated in our previous study for improvement of an angled sidewall which prevents the densification of FeRAM. In this study, the characteristics of platinum CMP for FeRAM applications were also investigated by an approach as bottom electrode materials of ferroelectric material in CMP patterning. The removal rate was increased from 24.81 nm/min by the only alumina slurry (0.0 wt% of H 2O 2 oxidizer) to 113.59 nm/min at 10.0 wt% of H 2O 2 oxidizer. Electrochemical study of platinum and alumina slurry with various concentrations of H 2O 2 was performed in order to investigate the change of the removal rate. The decreased particle size in the alumina slurry with an addition of 10.0 wt% H 2O 2 oxidizer made the improved surface roughness of the platinum thin films. Micro-scratches were observed in all polished samples. 相似文献
8.
铜的化学机械抛光(Cu-CMP)技术是ULSI多层金属布线结构制备中不可缺少的平坦化工艺.Cu-CMP后硅片表面的蝶形、侵蚀等平坦性缺陷将降低铜线的最终厚度和增大电阻率,从而降低器件性能和可靠性.而且可能进一步影响硅片的面内非均匀性(WIWUN),在多层布线中导致图案转移的不准确.本文介绍了对Cu-CMP平坦性的仿真、模拟和实验研究,并着重分析了碟形、侵蚀和WlWUN与抛光液、线宽和图案密度、抛光速度和载荷等相关参数的关系. 相似文献
9.
Many researchers studying copper chemical mechanical planarization (CMP) have been focused on mechanisms of copper removal using various chemicals. On the basis of these previous works, we studied the effect of slurry components on uniformity. Chemical mechanical planarization of copper was performed using citric acid (C 6H 8O 7), hydrogen peroxide (H 2O 2), colloidal silica, and benzotriazole (BTA, C 6H 4N 3H) as a complexing agent, an oxidizer, an abrasive, and a corrosion inhibitor, respectively. As citric acid was added to copper CMP slurry (pH 4) containing 3 vol% hydrogen peroxide and 3 wt% colloidal silica, the material removal (MRR) at the wafer center was higher than its edge. Hydrogen peroxide could not induce a remarkable change in the profile of MRR. Colloidal silica, used as an abrasive in copper CMP slurry containing 0.01 M of citric acid and 3 vol% of hydrogen peroxide, controlled the profile of MRR by abrading the wafer edge. BTA as a corrosion inhibitor decreased the MRR and seems to control the material removal around the wafer center. All the results of in this study showed that the MRR profile of copper CMP could be controlled by the contents of slurry components. 相似文献
10.
It is well known that within-wafer nonuniformity (WIWNU) due to the variation in material removal rate (MRR) in chemical mechanical
polishing (CMP) significantly affects the yield of good dies. The process control for a batch CMP operation is further complicated
by wafer-to-wafer nonuniformity (WTWNU) caused by MRR decay when a number of wafers are polished with the same unconditioned
pad. Accordingly, the present work focuses on modeling the WIWNU and WTWNU in CMP processes. Various material removal models
suggest that the MRR is strongly influenced by the interface pressure. It is also well known that the viscoelastic properties
of the pad play an important role in CMP. In the present work, an analytical expression for pressure distribution (and its
associated MRR) at the wafer-pad interface for a viscoelastic pad is developed. It is observed that under constant load, which
is typical during main polishing in CMP, the spatial distribution of the interface pressure profile may change with time from
edge-slow to edge-fast, depending on the combination of wafer curvature, down pressure, and pad properties. For constant displacement
operations, the pressure profile retains its edge-slow or edge-fast characteristics over time. The analytical model predictions
of MRR based on viscoelastic pad properties also correlate very well to existing experimental observations of MRR decay when
an unconditioned pad is used to polish a number of wafers. Based on these observations, it may be conjectured that the viscoelastic
material properties of the pad play a primary role in causing the observed MRR decay. The analytical results obtained in the
present work can also provide an estimation of evolution of thickness removal distribution over the entire wafer. This may
be used for determining the optimum thickness of the overburden material and its polishing time, and for effective control
of CMP processes. 相似文献
11.
Chemical-mechanical polishing (CMP) has been widely used in semiconductor production for a certain length period, but the process control of CMP still has a number of issues to be resolved. The process control of CMP has not been well established. A good process model is essential to a successful CMP integration into mass production. This paper describes the development of a data logging network system for a CMP process. This system helps engineers build proper process control models. This system consists of the following entities: CMP process equipment, several analog/digital I/O devices built into the equipment, film thickness and scratch measurement instrument, particle measurement facility, and an infrared thermometer. All of these are connected with a local area network. 相似文献
12.
In chemical mechanical polishing (CMP) of Cu, organic acids are often used as additives of slurries. This paper studied the effects of citric acid, oxalic acid, glycolic acid and glycine on Cu CMP performance. Our experiments explored the difference of these organic acids in surface reactions with Cu. The results showed that organic acids could chelate the passive film of Cu, and oxalic acid would further form precipitates with copper ions to change the chemical and mechanical action during CMP. Potential-pH diagrams, electrochemical polarization and impedance analyses were used to examine the behaviors of Cu in various organic acid slurries. The results indicated that the proposed equivalent circuits from impedance analysis for Cu CMP system could provide a good index to surface roughness. Furthermore, we also discussed the effects of used organic acids on reducing particle contamination after Cu CMP by measuring the difference of isoelectric points between Cu and α-Al 2O 3. The result showed that the addition of organic acid could efficiently decrease particle contamination. 相似文献
13.
We have studied the chemical mechanical polishing (CMP) characteristics of mixed abrasive slurry (MAS) retreated by adding of zirconium oxide (ZrO 2) abrasives within 1:10 diluted silica slurry. These mixed abrasives in the MAS are evaluated with respect to their particle size distribution, surface morphology, and CMP performance such as removal rate and non-uniformity. As an experimental result, the comparable slurry characteristics when compared to the original silica slurry were obtained from the viewpoint of high removal rate and low non-uniformity for excellent CMP performance. Therefore, our proposed ZrO 2-MAS can be useful to save on the high cost of slurry consumption since we used a 1:10 diluted silica slurry. 相似文献
14.
Chemical mechanical planarization (CMP) has been proved to achieve excellent global and local planarity, and, as feature sizes
shrink, the use of CMP will be critical for planarizing multilevel structures. Understanding the tribological properties of
a dielectric layer in the CMP process is critical for successful evaluation and implementation of the materials. In this paper,
we present the tribological properties of silicon dioxide during the CMP process. A CMP tester was used to study the fundamental
aspects of the CMP process. the accessories of the CMP tester were first optimized for the reproducibility of the results.
The coefficient of friction (COF) was measured during the process and was found to decrease with both down pressure and platen
rotation. An acoustic sensor attached to this tester is used to detect endpoint, delamination, and uniformity. The effects
of machine parameters on the polishing performance and the correlation of physical phenomena with the process have been discussed. 相似文献
15.
In the copper chemical mechanical polishing process, the mixed complexing ligands (glycine and disodium ethylene diamine tetraacetic acid (Na 2edta)) were utilized to enhance the polishing rate and to reduce the formation of Cu-BTA reabsorbed molecules, and the mixed dissolution inhibitors (benzotriazole and methylbenzotriazole) were applied to reduce the surface roughness. We propose that the enhanced polishing rate is due to the formation of easier removed water-soluble Cu-edta and Cu-glycine complexes, and the reduced surface roughness is mainly owing to the reduction of the Cu-BTA reabsorbed molecules and the formation of denser surface film based on complementary “space-filling” adsorption mechanism for Cu-BTA/TTA molecules. 相似文献
16.
Abrasive particles used in chemical mechanical planarization (CMP) of copper often agglomerate and cause scratches on the finished surface. Abrasive-free CMP offers a feasible solution to this problem, and our present work examines four dicarboxylic acids (oxalic, malonic, succinic and glutaric, with increasing carbon chain lengths) as possible complexing agents for such a chemically dominated CMP process. At pH 3.0-4.0, oxalic and malonic acids are most effective for abrasive-free Cu removal. The rates of Cu dissolution and polish (with or without abrasives) are correlated with pH dependent distributions of mono-anionic (for oxalic and malonic) and neutral (for succinic and glutaric) acid species. The surface morphologies of a Cu wafers obtained by abrasive-free CMP in these acids also are more defect free and flat compared to those obtained using abrasives. 相似文献
17.
目前半导体制造技术已经跨入0.13μm 和300mm时代,化学机械抛光(CMP)技术在ULSI制造中得到了快速发展,已经成为特征尺寸0.35μm以下IC制造不可缺少的技术。CMP是唯一能够实现硅片局部和全局平坦化的方法,但CMP的材料去除机理至今还没有完全理解、CMP系统过程变量和技术等方面的许多问题还没有完全弄清楚。本文着重介绍了化学机械抛光材料去除机理以及影响硅片表面材料去除率和抛光质量的因素。 相似文献
18.
Chemical mechanical polishing (CMP) has been widely accepted for the metallization of copper interconnection in ultra-large scale integrated circuits (ULSIs) manufacturing. It is important to understand the effect of the process variables such as turntable speed, head speed, down force and back pressure on copper CMP. They are very important parameters that must be carefully formulated to achieve desired the removal rates and non-uniformity. Using a design of experiment (DOE) approach, this study was performed investigating the interaction effect between the various parameters as well as the main effect of the each parameter during copper CMP. A better understanding of the interaction behavior between the various parameters and the effect on removal rate, non-uniformity and ETC (edge to center) is achieved by using the statistical analysis techniques. In the experimental tests, the optimized parameters combination for copper CMP which were derived from the statistical analysis could be found for higher removal rate and lower non-uniformity through the above DOE results. 相似文献
19.
化学机械抛光是硅片全局平坦化的核心技术,然而在实用阶段上,这项技术还受限于一些制造系统整合上的问题,其中有效的终点检测系统是影响抛光成效的重要关键.若未能有效地监测抛光运作,便无法避免硅片产生抛光过度或不足的缺陷.本文在介绍CMP机制与应用的基础上,系统分析了CMP终点检测技术的研究现状及存在的问题. 相似文献
20.
The effects of temperature, slurry pH, applied pressure, and polishing rotation rate on the material removal rate during chemical mechanical polishing (CMP) of 4H-silicon carbide wafers using colloidal silica slurry and polyurethane/polyester fiber polishing pads have been studied. Measured removal rates varied from around 100 Å/hr to nearly 2500 Å/hr depending on the values of the various parameters. The amount of material removed was determined by measuring the wafer mass before and after polishing. Variations in temperature and slurry pH did not produce significant changes in the measured removal rates. Higher polishing pressures resulted in increased material removal rates from 200 to 500 Å/hr but also produced excessive polishing pad damage. Variations in pad rotational speeds produced the largest changes in material removal rates, from around 200 to around 2000 Å/hr for rotational speeds between 60 and 180 rpm, but the variations were non-linear and somewhat inconsistent. This CMP formula is shown to consistently produce damage free surfaces but the optimum removal rate is slow. 相似文献
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