bluuebunny/crossref_metadata_2025_split huggingface dataset:
Particle Metrology in CMP Slurries - Potential and Limitations of Relevant Measuring Methods
Authors: Stintz Michael , Barthel Herbert , Moinpour Mansour 
Published: April 2011

ABSTRACTThe design of nanostructured materials like CMP slurries on an industrial scale requires the control of disperse systems of nanoparticles as well as of single isolated "bad" particles . It is well known that slurry abnormalities resulting from large abrasive particles and abrasive particles agglomeration can cause defects on wafer surfaces during CMP.Particle-particle interactions generate secondary nanometer structures, clusters or agglomerates, which can dominate the relevant properties of the bulk material. Size and structure of these particle agglomerates/structures are the result of a dynamic equilibrium between agglomeration and desagglomeration. There is still a lack of understanding of these secondary soft nano- up to micro- particles because no adequate characterization methods are established.Dilution and other preparation treatment to enable analysis by laboratory methods like TEM or AFM will distort the interparticle forces and will generate artifacts. Hence characterization methods are under investigation which can tolerate a high number of particles in the sensing zone. These high concentration methods often deliver ambiguous results. Consequently different physical principles have to be combined to get unambiguous information on the disperse state.Performance characteristics of ultrasonic spectroscopy, photon correlation spectroscopy, analytical photo-centrifugation method combined with the high spatial resolution as well as special single particle optical counters are discussed on examples.
Advances in the Characterization of Particle Size Distributions of Abrasive Particles used in CMP
Authors: Kamiti Mungai , Popadowski Stacey , Remsen Edward E. 
Published: April 2011

ABSTRACTThe use of density gradient stabilized centrifugal sedimentation (disc centrifugation) for the characterization of abrasive particles in CMP slurries is reported. For slurries prepared with ceria and colloidal silica abrasives, the technique is demonstrated as capable of providing highly repeatable analyses of the abrasive's apparent particle size distribution (PSD). The addition of water soluble organic additives to the slurries is shown to produce large shifts in the apparent PSD relative to the PSD of the pure abrasive particles. Particle-additive interactions driving the shift in apparent PSD could not be interpreted with confidence due to the lack of accurate densities for particle-abrasive complexes formed in the slurry. To address this problem, sucrose density gradients prepared using H2O and D2O were tested as spin fluids of different densities to analyze a colloidal silica standard with a narrow PSD. Preliminary results comparing experimental disc centrifuge data with theoretical simulations of the disc sedimentation pattern suggest that this technique can potentially characterize both the particle diameter and density of abrasive particles in a CMP slurry.
Particles as Transport Carriers in CMP Slurries
Authors: White Daniela , Parker John , Li Shuyou , Dravid Vinayak 
Published: April 2011

ABSTRACTNanoparticles provide multiple functionalities to the performance of CMP slurries. These include mechanical surface abrasion, mass transport of slurry chemistries between the pad and wafer surface, or increased chemical reactivity of some key additives by in-situ interactions with the particles surfaces. Since most of the inorganic nanosized oxides used as common abrasives in CMP slurries (silica, alumina, ceria) have chemically reactive hydrophilic surface functionalities in a large pH range (2 – 12), we can assume that significant interactions between the inorganic particles surface and some of the slurry additives (organic surfactants, oxidizers, film-forming ligands, removal rates promoters, etc.) could have a meaningful impact on slurry ultimate performances (removal rates, planarity, defectivity, etc.)In this presentation we will highlight the significance of slurry abrasives as surface modified nanoparticles/chemical carriers, able to directly participate and control the metal oxidation/removal mechanism, removal rates and other polishing characteristics. We will discuss two relevant examples, both involving fumed silica as the carrier particle in two different low pH slurries of variable complexities in terms of design (with/without particles surface modifiers) and performance requirements for tungsten CMP. We will provide a complex variety of analytical evidence (TEM, SEM, FT-IR, GPC, cyclic voltammetry, MS-TOF) in order to support the proposed mechanism of “chemically activated fumed silica”, in its natural (no interactions with organic additives in the slurry) and surface modified form (in-situ interactions with organic additives), as a carrier of selective slurry components with enhanced chemical activity, that ultimately controls the tungsten CMP mechanism and the ability of the slurry to efficiently and predictably remove the oxidized tungsten film formed at the wafer surface.
An Approach to Modeling Particle-Based and Contact-Based Wear in CMP
Authors: Terrell Elon Jahdal , Kuo Michael , Higgs C. Fred 
Published: April 2011

ABSTRACTA volume-pixel, or “voxel”-based wear model was developed in order to predict feature-scale wear in chemical-mechanical polishing (CMP), and was compared to the measured evolution of lithographically-patterned features during full-scale CMP tests. In order to conduct this study, a lithographic technique was used in order to pattern a set of raised square features into Cu-coated silicon wafers. A two-dimensional (2D) contact profilometer was used to measure the topography of an isolated feature on the wafer both before polishing and at various intervals throughout the polishing process. For wear modeling, the voxel modeling framework involved the conversion of each of the pre-polished feature topographies into a square matrix of cuboids, which allowed for contact mechanics and wear modeling to take place between the interacting cuboids of the sample and a simulated polishing pad. After the predicted wear of the Cu feature was then compared to experiment.
Cu Post-CMP Displacement Cleaning: A Mechanistic Product Development Approach Based on Selected Thermodynamic and Kinetic Data
Authors: Peters Darryl Wayne 
Published: April 2011

ABSTRACTA mechanistic product development approach will be presented that utilized selected thermodynamic and kinetic data for development of a Cu post-CMP cleaner for use after polishing with either high or low pH slurry. A Pourbaix diagram offers the thermodynamically stable Cu species vs. pH and open circuit potential (OCP) for an aqueous cleaner. Pourbaix diagrams do not provide any information on the kinetics for dissolution of water soluble species. Cu oxide dissolution rates were measured using an electrochemical cell. Deposition and removal rates for benzotriazole (BTA) and 1,2,4-triazole (TAZ) were measured using an electrochemical cell with a quartz crystal microbalance (QCM). Passivator film deposition was investigated to determine the film type and thickness resulting from a typical CMP process. BTA and TAZ films deposited near neutral pH were thicker than those deposited at high pH. TAZ films were significantly thinner (∼20Å) than BTA films deposited under similar conditions, approaching a self assembled monolayer (SAM). The BTA removal rate for a citrate solution with a pH of 4 was 20Å/min., an order of magnitude lower than that for TMAH-containing solutions. The TAZ removal rate for an oxalate solution with a pH of 4 was 240Å/min., which was twice the removal rate for BTA deposited under similar conditions. An appropriate TAZ solution was found to displace BTA on Cu and leave a hydrophilic, thin (∼20Å) passivating layer of TAZ. Other Cu passivators were also examined but only TAZ protected all Cu crystallographic orientations observed. BTA, 5-aminotetrazole (5-ATA) and 4-carboxybenzotriazole (CBTA) did not protect some Cu crystal orientations, leading to etching of entire grains and increased surface roughness. BTA and CBTA yielded hydrophobic Cu surfaces, leading to surface wetting issues and the potential for watermarks. A new alkaline Cu post-CMP cleaner was developed to remove residues resulting from slurries, regardless of their pH, which utilizes TAZ to displace BTA and protect Cu, significantly lower organic defects, reduce surface roughness, provide a hydrophilic Cu surface, and significantly extend the staging time allowed between the clean process and subsequent wafer processing.
New Particle Metrology for CMP Slurries
Authors: Williams Kim , Park Ilyong , Remsen Edward E. , Moinpour Mansour 
Published: April 2011

ABSTRACTA new particle sizing and counting method based on the coupling of flow field-flow fractionation (FFF) with dual-sensor, single particle optical sensing (SPOS) detection is reported. The integration of FFF and SPOS systems was accomplished by means of a dilution interface that preserved the resolution of FFF-separated particles. Analysis of a model mixture of polystyrene latex standards of different diameters established that the FFF-SPOS system can resolve particles into discrete peaks for subsequent particle counting. Application of this method for the analysis of a colloidal silica standard demonstrated its use for materials commonly employed as CMP abrasives. Further development and refinement of the technique will enable compositional and structural analyses of heterogeneous large particle populations constituting commercial CMP slurries.
Improved Defect Classification Techniques of a Laser Scattering Detection System for Post CMP Silicon Dioxide Wafers
Authors: Mateja Daniel , Kasai Toshi , Denham Michael , Siriwardane Haresh 
Published: April 2011

ABSTRACTA laser light scattering technique was used for the identification of defects on silicon dioxide (SiO2) wafers polished with a tungsten CMP slurry. Defects were then classified as scratches and particles using scanning electron microscopy (SEM). The effects of the incident beam illumination and scattering geometry on the defect detection are examined. Appropriate experimental conditions for selective detection of scratches and particles are discussed in conjunction with the estimated defect count and fractional ratio for specific defect types and sizes. The findings are qualitatively consistent with predicted light scattering distributions simulated from silicon bare substrates.
A Study in Selectivity Variations of WCMP Slurries Related to pH, ζ[zeta]-potential and Dilutions with De-ionized Water
Authors: Gianni Davide , Ardizzone Silvia , Cappelletti Giuseppe , Maspero Angelo , Monticelli Damiano , Spinolo Giulia , Masciocchi Norberto 
Published: April 2011

ABSTRACTCommercially-available WCMP slurries perform differently under diverse modifications: pH variations, dilutions, ageing, etc. In order to understand the physico-chemical basics of the mechanism and selectivity of these slurries, we have performed a number of measurements, including determination of effective CMP removal rates on blank and patterned wafers. The results of the performances of the different modifications have been compared, and a few optimized conditions and recipes derived. Our results surprisingly show that pH has a much greater influence on the removal rate of tungsten and silicon dioxide than the particles content, and that the way a certain pH is reached (or maintained) significantly affects the performances of the prepared slurries.We propose that nitric acid can be used to dilute selective slurries in order to keep high removal rates. Indeed, diluting slurries with an acidic solution of the same pH maintains particle charges far from zero, and keeps oxidizing conditions stable. However, the effects of the acidic dilution of the slurries include a slight reduction of removal rate and a decrease in defect density
Enabling Damascene Solutions for 45 nm Beyond
Authors: Tsujimura Manabu 
Published: April 2011

ABSTRACTThere are several technology developments, which should have been completed in CN 65 nm (Commercial node) device development, but passed over to CN 45 nm device development. Seven items relating with damascene process, especially connecting with planarization process, are nominated and introduced herein including new advent technologies as enabling solutions for CN 45 nm. First one is low-down-force planarization. Although there are several planarization technologies such as CMP (Chemical Mechanical Polisher), ECMP (Electrical Chemical Mechanical Polisher), ECP (Electrical Chemical Polisher), CE (Chemical Etching) and those combination technologies, it is not decided which is the best one and how low down force is optimized taking into account of CoC (Cost of Consumable) issues. In this report, all planarization technologies are explained using ‘General Principle governing all planarization technologies’, and allowable down force is suggested through stress analysis and fracture toughness analysis. Second one is direct polish on ULK. There may be two approaches. One is to adopt CMP hard mask which dielectric constant would not be changed by direct polish. In this case, non-uniformity of CMP in this hard mask is important. Second is to polish directly on ULK, which dielectric constant would be changed by CMP, then restoration technology should be discussed at a same time. Third one is Ru liner application. When is this technology required? Deposition for Ru seed and polishing of Ru integration are reported. Forth one is watermark free drying of ULK. Vacuum drying and IPA drying (Rotagoni) which is necessary for hydrophobic surfaces are reported. Fifth one is cleaning technologies for less than 45 nm FM. After CN 45 nm, it is difficult to distinguish several defects such as scratches or FM. In this case, soft cleaning methods such as non-contact cleaning would be required. Cavitation jet as one of non-contact type cleanings is reported with its cleaning results. Sixth one is Co-W cap process. Electro-less metal cap technology in order to enhance EM is reported. CMP after Co-W deposition may be useful in order to clean cap surfaces. Seventh one is starting material such as nanotopography and roll off which would affect on CMP performances.
Effects of Additives in KOH Based Electrolytes on Cu ECMP
Authors: Kwon Tae-Young , Kim In-Kwon , Park Jin-Goo 
Published: April 2011

ABSTRACTThe purpose of this study was to characterize KOH based electrolytes and effects of additives on electro-chemical mechanical planarization. The electrochemical mechanical polisher was made to measure the potentiodynamic curve and removal rate of Cu. The potentiodynamic curves were measured in static and dynamic states in investigated electrolytes using a potentiostat. Cu disk of 2 inch was used as a working electrode and Pt electroplated platen was used as a counter electrode. KOH was used as the electrolyte. H2O2 and citric acid were used as additives for the ECMP of Cu. In static and dynamic potentiodynamic measurements, the corrosion potential decreased and corrosion current increased as a function of KOH concentration. In dynamic state, different potentiodynamic curve was obtained when compared to the static state. The current density did not decrease in passivation region by mechanical polishing effect. The static etch and removal rate were measured as function of KOH concentration and applied voltage. In ECMP system, polishing was performed at 30 rpm and 1 psi. The removal rate was about 60 nm/min at 0.3 V when 5 wt% KOH was used. Also, the effect of additive was investigated in KOH based electrolyte on removal rates. As a result, The removal rate was increased to 350 nm/min when 5wt% KOH, 5vol% H2O2, 0.3 M citric acid were used.
ECMP Enhances the Planarization Efficiency — a Phenomenon of Reverse Topography during Cu Removal
Authors: Liu Feng Q , Hsu Wei-Yung , Duboust Alain , Chen Liang 
Published: April 2011

ABSTRACTPlanarization efficiency is a key parameter to evaluate the process effectiveness of CMP. When the Cu thickness was removed beyond the step height, under certain conditions, the recessed trenches become protruded, resulting in reverse topography. This reverse topography during bulk Cu removal can only be attributed to the low down force polishing, electrical driving Cu removal and Cu passivation mechanism in ECMP process. In this paper, the concept of reverse topography is introduced and the removal selectivity difference on the trench area and field area during bulk Cu removal is discussed. In ECMP, a “real” 100% planarization efficiency can be achieved when the Cu thickness removed is less than the trench step height. This new understanding in planarization efficiency sheds lights on ways to improve CMP productivity
Application of Scatterometry to BEOL Measurements: Post Cu CMP Measurements
Authors: Kulkarni Deepak , Ponoth Shom , Wu Li , Fang Rui , Liu Xiaoping , Elia Alex 
Published: April 2011

ABSTRACTWith shrinking interconnect dimensions, as a result of scaling, resistance variations in percentage terms are increasing. Quick and reliable measurements on the interconnect structures are the first step to the detection and implementation of a process-control strategy in order to reduce process related variations. This paper discusses the application of Optical Digital Profilometry (ODP) to the measurement of BEOL parameters, specifically the measurement of post copper-CMP metal dimensions with the intention of understanding CMP related contribution to resistance variations. Traditionally a combination of electrical test, optical metrology and profilometry is needed to understand the contribution of CMP to the interconnect and inter-layer-dielectric (ILD) dimensions. This paper discusses the successful use of ODP to model and measure the dimensions of both the metal and the dielectric in nested patterned structures with different pattern densities for a single level patterned build. Hence this technique could potentially simplify and replace multiple measurement techniques and help in quickly providing relevant information for process monitoring and control.
Influence of Oxygen Annealing on Electrical Properties of ZnO:Cl Thin Films
Authors: Tchelidze Tamar , Chikoidze Ekaterine , Jomard Francois , Gorochov Ouri , Galtier Pierre 
Published: April 2011

AbstractThe influence of oxygen treatment on carrier transport properties of pure ZnO and ZnO:Cl thin films grown by MOCVD were studied. The experimentally obtained values of carrier concentrations after oxyden treatment at different temperatures, were compared with the the results obtained from thermodynemical analysis of the system: ZnO:Cl-Oxyen vapour pressure, using method of quasi-chemical reactions (QCR).
Evidence of the De-multiplication Interactions Between Threading Dislocations in GaN Films Grown on (0001) Sapphire Substrates
Authors: Wang Cheng-Liang , Gong Jyh-Rong 
Published: April 2011

AbstractWe report the observation of threading dislocation de-multiplication process by transmission electron microscopy (TEM). The GaN films used in this study were grown on (0001) sapphire substrates with LT-GaN buffer layers by reduced pressure organometallic vapor phase epitaxy. By using g · Db = 0 invisibility criterion, it was found that some of TDs were de-multiplicated by interactions among themselves. In particular, type a+c TDs were found to nucleate through the interactions between type a and type c TDs in GaN near the GaN/sapphire interface so that the de-multiplication of TDs in GaN films was achieved.
Characterization of Nanocavities in Silicon Using Small Angle X-Ray Scattering
Authors: Dunmont Myriam , Coulet Vanessa , Regula Gabrielle , Bley Françoise 
Published: April 2011

AbstractThe techniques of small angle X-ray scattering and transmission electron microscopy are applied to characterize the size distribution of nanocavities in a (111) Si wafer multi-implanted with He+ in the Mev range energy. The comparison between both methods shows that they all give access to the same structural information but small angle X-ray scattering additionally offers the possibility to monitor the cavity size distribution during a thermal treatment. Moreover, providing that the collected data are of good quality, the former method also allows the knowledge of the porosity of the implanted Si wafer.
Cathodoluminescence Study of V-defects in AlGaAs-based High-power Laser Bars
Authors: Pommies Matthieu , Avella Manuel , Martin Alonso , Jimenez Juan , Oudart Myriam , Nagle Julien 
Published: April 2011

AbstractHigh-power semiconductor lasers are required to be more and more powerful, efficient and reliable for applications such as solid-state lasers pumping, materials processing, and thermal printing among others. The understanding of the degradation mechanisms is essential to improve the high power laser reliability. The highest power emission is achieved with multi-emitter laser cm-bars, which present problems related to packaging induced stress. A very harmful defect in this type of devices is the so-called V defect. We present herein a study of these defects using cathodoluminescence imaging, the role of packaging is discussed.
DLTS: A Promising Technique for Understanding the Physics and Engineering of the Point Defects in Si and III-V Alloys
Authors: Khan Aurangzeb , Yamaguchi Masafumi 
Published: April 2011

AbstractDeep level transient spectroscopy (DLTS) is the best technique for monitoring and characterizing deep levels introduced intentionally or occurring naturally in semiconductor materials and complete devices. DLTS has the advantage over all the techniques used to-date in that it fulfils almost all the requirements for a complete characterization of a deep centre and their correlation with the device properties. In particular the method can determine the activation energy of a deep level, its capture cross-section and concentration and can distinguish between traps and recombination centers.In this invited paper we provide an overview of the extensive R & D work that has been carrier out by the authors on the identification of the recombination and compensator centers in Si and III-V compound materials for space solar cells. In addition, we present an overview of key problems that remain in the understanding of the role of the point defects and their correlation with the solar cell parameters.
Schottky Barrier Height Engineering in NiGe/n-Ge(001) Contacts by Germanidation Induced Dopant Segregation
Authors: Liew S. L. , Chua C. T. , Seng D. H. L , Chi D. Z. 
Published: April 2011

AbstractSchottky barrier height (ÖB) engineering of NiGe/n-Ge(001) diodes was achieved through germanidation induced dopant segregation on As implanted-Ge substrates. was reduced from 0.55 eV to 0.16 eV with increasing As dose on n-Ge(001) while on p-Ge(001), the diodes exhibited increasing ÖB.
Defect Reduction and Its Mechanism of Selective Ge Epitaxy in Trenches on Si(001) Substrates Using Aspect Ratio Trapping
Authors: Park Ji-Soo , Bai J. , Curtin M. , Adekore B. , Cheng Z. , Carroll M. , Dudley M. , Lochtefeld A. 
Published: April 2011

AbstractDefect-free germanium has been demonstrated in SiO2 trenches on silicon via aspect ratio trapping, whereby defects arising from lattice mismatch are trapped by laterally confining sidewalls. Results were achieved through a combination of conventional photolithography, reactive ion etching of SiO2, and selective growth of Ge as thin as 450 nm. It was revealed that facets, when formed early on in the growth process, play a dominant role in determining the configurations of threading dislocations in the films. This approach shows great promise for the integration of Ge and/or III-V materials, sufficiently large for key device applications, onto silicon substrates.