Scratch Reduction Research Articles

Restricted hydrolysis reaction of Si3N4 via nonionic polymer adsorption in advanced shallow trench isolation chemical mechanical planarization

The adoption of ultra-fine nanoparticles as an abrasive has garnered notable attention in shallow trench isolation (STI) chemical mechanical planarization (CMP) due to its potential in scratch reduction. However, the poor removal rate, attributed to the physicochemical interaction between abrasive and conventional organic passivation agent, limits the introduction of ultra-fine nanoparticles. Here, a nonionic polymer polyvinyl alcohol (PVA), without particle interaction, is proposed as a novel passivation agent to restrict the hydrolysis reaction of Si3N4 film in the advanced STI CMP process. The selective adsorption of PVA onto the Si3N4 film lowers its removal rate by suppressing the hydrolysis reaction via hydrogen bonding while the removal rate of SiO2 film remains constant. Moreover, the uniformity of SiO2 removal is improved due to the enhanced fluidity of slurry, resulting from increased wettability between pad and slurry. As a result, the removal selectivity between both films has been improved to 113.4:1 and the in-wafer-uniformity (IWU) of SiO2 film is supplemented by 96.8 % simultaneously.

Scratch Reduction in Polystyrene Beads and Capsules via Alternative Flask Material Testing

Polystyrene (PS) capsules produced by General Atomics are useful to inertial confinement fusion work. Contact scratches caused by collisions between container asperities and PS capsules and beads are a prominent defect arising during the fabrication process, and reducing them would improve surface quality. This study analyzed various containers for the curing and washing stages of PS bead and capsule production. For the curing stage, plastic bottles were found to have lower scratch frequency and severity than glass flasks, indicating that they may be a better alternative. For the washing stage, plastic or Gel-Pak washing containers demonstrated no reduction in scratch frequency when compared to glass washing containers.

Imaging Analysis of Scratch Reduction in Poly (Methyl Methacrylate) (PMMA) Plastic with NOVUS Polishing Products

ABSTRACT Remediation of disfiguring scratches and abrasions on aging plastics challenges even the most experienced conservator. This study assesses the effect of three NOVUS polishing products on remediation of poly (methyl methacrylate) (PMMA). Samples were prepared to mimic the depth and type of scratches observed during conservation treatment performed on vacuum-formed reliefs from the 1960s. The study compares samples of new/unaged PMMA to naturally aged PMMA samples. Two different methods were successfully used to assess the polishing efficacy, which is notoriously challenging to document in transparent and reflective media: (1) image segmentation analysis of photographs to yield scratched area fractions, using three approaches (Li-thresholding, random forest, and convolution neural network); and (2) optical profilometry measurements, which provide surface root-mean-square roughness (RRMS) values. Both methods support the qualitative observations that polishing with the abrasive NOVUS products significantly reduced the surface damage; scratch area fractions decreased from 50–60% to 1–5% across the aged PMMA types after treatment, corresponding to an ∼85% decrease in surface roughness. Critically, the two methods are complementary: the image segmentation results demonstrated a greater visible difference between two degrees of polishing treatments on the new material, while profilometry results were able to parse differences in the degree of scratch reduction between the aged and new materials.

A nanoclustered ceria abrasives with low crystallinity and high Ce3+/Ce4+ ratio for scratch reduction and high oxide removal rates in the chemical mechanical planarization

A nanoclustered ceria abrasives with low crystallinity and high Ce3+/Ce4+ ratio for scratch reduction and high oxide removal rates in the chemical mechanical planarization

Synergy between dodecylbenzenesulfonic acid and isomeric alcohol polyoxyethylene ether for nano-scale scratch reduction in copper chemical mechanical polishing

In this paper, dodecylbenzenesulfonic acid (DBSA) and isomeric alcohol polyoxyethylene ether (iAEO) are tested as additives to basic silica-based slurries with the goal of reducing scratching during copper chemical mechanical polishing (CMP) in 14 nm ultra large scale integration. DBSA and iAEO can reduce scratch defects by more than 86% and exhibit stable scratch densities over 14 h of pad lifetime. Various analytical results including particle size distributions, large particle counts, dynamic mechanical analyses, and scanning electron microscope data reveal that the synergistic effects of DBSA and iAEO may improve particle dispersibility, enhance tribological behavior, increase pad water uptake, and effectively remove polishing byproducts from the pad.

Complementary roles of murine NaV1.7, NaV1.8 and NaV1.9 in acute itch signalling

Acute pruritus occurs in various disorders. Despite severe repercussions on quality of life treatment options remain limited. Voltage-gated sodium channels (NaV) are indispensable for transformation and propagation of sensory signals implicating them as drug targets. Here, NaV1.7, 1.8 and 1.9 were compared for their contribution to itch by analysing NaV-specific knockout mice. Acute pruritus was induced by a comprehensive panel of pruritogens (C48/80, endothelin, 5-HT, chloroquine, histamine, lysophosphatidic acid, trypsin, SLIGRL, β-alanine, BAM8-22), and scratching was assessed using a magnet-based recording technology. We report an unexpected stimulus-dependent diversity in NaV channel-mediated itch signalling. NaV1.7−/− showed substantial scratch reduction mainly towards strong pruritogens. NaV1.8−/− impaired histamine and 5-HT-induced scratching while NaV1.9 was involved in itch signalling towards 5-HT, C48/80 and SLIGRL. Furthermore, similar microfluorimetric calcium responses of sensory neurons and expression of itch-related TRP channels suggest no change in sensory transduction but in action potential transformation and conduction. The cumulative sum of scratching over all pruritogens confirmed a leading role of NaV1.7 and indicated an overall contribution of NaV1.9. Beside the proposed general role of NaV1.7 and 1.9 in itch signalling, scrutiny of time courses suggested NaV1.8 to sustain prolonged itching. Therefore, NaV1.7 and 1.9 may represent targets in pruritus therapy.

Experimental investigations on magnetic abrasive finishing of Ti-6Al-4V using a multiple pole-tip finishing tool

Surface finishing plays a critical role in product manufacturing. This paper aims to evaluate the magnetic abrasive finishing (MAF) process in achieving nano-finishing on Ti-6Al-4V workpiece. An improved finishing tool–integrated multiple pole-tip is fabricated to perform the surface finishing of Ti-6Al-4V workpieces. Finite element analysis of the variation of magnetic field intensity in the finishing region demonstrates obvious formation of magnetic brush based on the simulation model. The simulation results are confirmed by experimental measurements, where it shows a good agreement. Finishing experiments for Ti-6Al-4V workpieces are carried out using an established platform, aiming to investigate the effects of varying the spindle rotational feed, the rotary table speed, and the working gap on surface roughness (Ra). The surface roughness of 0.073 μm was achieved from the initial 1.195 μm based on the finishing parameters of 900-rpm spindle rotational speed, 160 r/min rotary table speed, and 0.7-mm working gap, which improved by over 94%. The surface quality was improved significantly with scratch reduction.

Role of Dispersant Agent on Scratch Reduction during Copper Barrier Chemical Mechanical Planarization

The chemical mechanical planarization (CMP) has been one of the major manufacturing process to provide global and local surface planarizations in integrated circuits (IC) fabrications. Defects such as micro-scratches generated during CMP can lead to severe circuit failure, which affects yield. In the present work, ethoxylated decylalchohol (EDA) was used as dispersant agent to prevent the particles agglomeration to reduce scratches. Firstly, the effect of EDA on particle size distribution (PSD) of the slurry was investigated by dynamic light scattering (DLS) method. Then the effect of EDA on large particle counts (LPC) was studied through a dual sensor single particle optical sensing (SPOS) analysis method. The wetting ability of slurries as a function of EDA concentration was also studied. Finally, the defect scan tool and scanning electron microscope (SEM) reviewer were used to identify the scratch defects. The results show that the addition of EDA into the slurry can enhance the dispersity of colloidal silica abrasives and significantly reduce the number of large particles in the slurry, the SEM review results show that the scratch counts remarkably decreases with EDA concentration increasing. It can be demonstrated that the EDA can effectively reduce the scratch counts.

Post Cleaning for FEOL CMP with Silica and Ceria Slurries

For the manufacturing of Si-based semiconductors, CMP is utilized extensively to enable FEOL process integration such as STI, deep-trench, ILD, and poly-open. Silica slurries are usually adopted for bulk oxide polish while ceria slurries are more suited for the final “buff” polish where high selectivity to nitride is required. The ever stringent requirement for scratch reduction leads to the trend of using nano-sized abrasive particles in all types of CMP slurries. However, the stronger adhesion force between these nanoparticles and wafer surface necessitates the re-design and optimization of post-CMP processes to meet the low PR/FM defect requirement. The selection of proper chemicals is often the first step towards post-CMP cleaning. However, design of cleaning sequence, exploitation of the tool hardware, and optimization of operating parameters are equally critical to achieve maximum cleaning efficiency. As shown in Fig. 1, for an oxide or poly-Si CMP process with an acidic silica-based slurry, a preferred post cleaning process should operate in alkaline environment (e.g., pH 8~10) in order to build in repulsive zeta potential for easy of particle removal from wafer surface. In this case, the use of an acidic pCMP chemical would be unfavorable from zeta-potential point of view. Replacement of acidic chemical with just DIW (pH ~ 7) leads to significant reduction in PR/FM. In addition, optimization of the directionality, spin rpm, arm oscillation speed…etc, helps eliminate the wafer center-heavy signature and reduces the defect count further down. For FEOL CMP with ceria-based slurry running on a 3-platen polisher with serial meg tank/brush cleaning module, one can design the pCMP process based on the unique “reactive” nature of ceria abrasives, and also fully exploit the available hardwares and their process parameters. In this example, the POR process adopts only DIW in the meg tank. The go-to process, however, replaces DIW with a diluted acidic oxidizer so as to neutralize the reactive ceria abrasives, making it much easier to dislodge the particles from oxide wafer surface. The significant FM NADD reduction with the go-to pCMP process illustrates the efficiency of adding the meg clean step with diluted oxidizer. Further PR/FM reduction can be realized by optimizing the hardware and machine parameters such as those listed in Fig. 2, from on-platen buff clean all the way to the terminal step of Maragoni drying. Furthermore, for a new pCMP process to be considered production-ready, run order effects, repeatability, and CoO reduction need to be taken into account as well. In addition, post-clean surface analyses are carried out to ensure no potential reliability concern. Reference: W.-T. Tseng, J. Hagan, K. Mohan, R. Hull, J. MacDougall, R. Murphy, L. Tai, S. Molis, “Post Cleaning and Defect Reduction for Tungsten Chemical Mechanical Planarization” ICPT, 2015. Figure 1

Slurry Delivery Loop Optimization for Micro Scratch Reduction in Cu CMP

The effect of the slurry delivery loop on micro scratch defects in Cu CMP was investigated. Three different kinds of slurry delivery loops were designed. Test results showed that the third slurry delivery loop was the best and reduced micro scratch defects by more than 90%, compared with the first one.

(Invited) CMP Challenges toward DRAM Device below 20nm Technology

Below 30nm DRAM device technology, we currently have been facing so many challenges such as chip size reduction, particle size reduction, cost reduction and process step reduction. As chip size gets smaller and smaller, manufacturing processes would be very difficult due to particles and affecting defects. Relating to these, some aspects of the chemical mechanical polishing (CMP) processes we are currently challenging were studied case by case. We approached three kinds of techniques toward below 20nm technology. Scratch reduction techniques were reviewed and extreme edge control method by new head tool was introduced and finally nano-colloidal slurry was successfully evaluated for next devices. We would like to emphasize that most important thing is to cooperate with world-wide suppliers and work hand in hand with our chip makers to overcome challenges below 20nm technology.

A study of the relationship between stick-slip and micro-scratches generation during chemical-mechanical polishing process

An observation on the relationship between stick-slip phenomena and chatter scratch generation during chemical-mechanical polishing (CMP) was made using finite element analysis. The motivation for this work is based on the questions about the possibility of the stick-slip phenomena in the CMP process and the quantitative relation between the stick-slip behaviors and the formation characteristics of the scratch. The finite element simulation results showed that stick-slip friction could occur during CMP and it could be seen only in the case of the interactions with the particles trapped inside pad surface. Also, the stick-slip period increased with the density of interacting wafer surface material and the particle size had a significant effect on the stick-slip period and magnitude. It is expected that this work will aid the development of chatter scratch reduction technology.

Effect of pad surface roughness on material removal rate in chemical mechanical polishing using ultrafine colloidal ceria slurry

In this paper, effect of ultrafine ceria (UFC) particle of which size is as small as 20 nm on CMP performance was investigated. Compared to conventionally used 100 nm abrasive particle which is made by calcination process, almost 80% scratch reduction was obtained by using UFC. However, a UFC slurry showed unstable material removal rate behavior from less than 200 A/min to over 2000 A/min, depending on polishing pad surface characteristics. As pad surface roughness increases, oxide removal rate using UFC drops abruptly to less than 200 A/min. In order to use UFC for scratch reduction, the pad surface roughness optimization is necessary to avoid a sudden drop in the removal rate. This study gives a possible boundary for pad surface roughness for UFC application for CMP.

Reduction of Scratch on Brush Scrubbing in Post CMP Cleaning by Analyzing Contact Kinetics on Ultra Low-k Dielectric

Damage reduction during planarization is strongly required to avoid scratch generation leading to yield loss in an integrated circuit fabrication especially after implementation of ultra low-k dielectrics in Cu damascene structure. By analyzing contact characteristic on the advanced non-porous ultra low-k dielectric, fluorocarbon film, brush scrubbing at high rotation rate and low down pressure is proposed to satisfy both particle removal efficiency and scratch reduction in post CMP cleaning. Shear force increases with increasing in brush rotation rate because of enlargement of pressured area which is generated by fluid flow. Enhancement of contribution of fluid flow by increasing brush rotation rate with lowering down force to particle removable efficiency can be direction for future low-k compatible process.

Buspirone for Stereotypic Movements in Elderly With Cognitive Impairment

Buspirone for Stereotypic Movements in Elderly With Cognitive Impairment

A Study on tole Improvement of the Slurry Dispersibility in CMP

This study presents the possibility of scratch reduction on wafer in CMP by applying the ultrasonic and megasonic energy into the slurry which might contain large abrasive particles. Experiments were conducted to verify the dispersion ability of agglomerated particles by applying ultrasonic, megasonic waves and analyze the particle distribution of used slurry in case, of sonic energy assisted or none. And the dispersion stability of megasonic waves was investigated through the experiment of stability of the dispersed slurry, Finally, to confirm that the distribution of particles in slurry by ultrasonic waves was actually related to scratches on wafer when CMP was done, tungsten blanket wafer was processed, by CMP to compare and investigate scratches on wafer.

Measuring fear and anxiety in the marmoset ( Callithrixpenicillata) with a novel predator confrontation model: effects of diazepam

This report describes a new experimental method for measuring fear and anxiety in Cerrado marmosets ( Callithrix penicillata). In order to test the sensitivity of the behavioral parameters to an anxiolytic substance, the effects of the benzodiazepine diazepam on the anxiety measures were examined. The strategy was to use a naturally occurring stimulus known to elicit anxiety and fear in this species. A taxidermized predator (the wild cat Felis tigrina) was chosen as the stimulus to induce anxiety-related behaviors on the basis of a preceding study in which various stimuli were systematically compared in their effectiviness to induce fear responses. The apparatus consisted of three parallel arms of equal dimensions, joining two perpendicular arms at each end, thus comprising a figure eight-like or five-arm continuous rectangular maze. The wild-cat was placed outside of one corner of the maze’s outer parallel arms. Each subject was submitted to six treatments given in random order: three drug sessions (diazepam 1, 2 and 3 mg/kg, IM), saline, sham (injection control), and a control session, involving neither manipulation nor injection. Subjects were placed into the back of the chamber, out of sight of the ‘predator’, 20 min after a treatment and given free access to the maze for 30 min. The behavioral repertoire was recorded via videocamera. The following behaviors were considered to be possible indices of emotionality relevant to exposure to the predator in the paradigm used: scratching, scent marking, exploration, frequency and time spent in each of 13 defined sections of the maze. Administration of diazepam induced a significant reduction in scratching and an increase in the time spent in the vicinity of the ‘predator’, as well as in the frequency of exploratory behaviors, indicative of an anxiolytic effect. Gender did not influence the effect of treatment. These results suggest that this new ethologically-based test may be a useful method for studying anxiety and fear-induced avoidance in non-human primates and for pre-clinical research on psychoactive drugs.

Marmoset Conspecific Confrontation: An Ethologically-Based Model of Anxiety

A method of measuring confrontation-induced behavioural changes in common marmosets ( Callithrix jacchus) together with automated monitoring of locomotor activity has been developed as a possible model of anxiety. Recording both affiliative and agonistic behaviours between male/female pairs of marmosets and using diazepam as a reference drug, it has been possible to define a profile of behavioural changes which could be regarded as representing an anxiolytic response. Unfamiliar male/female pairs of marmosets were brought into close (non-contact) proximity in a controlled environment, in which their locomotor activity was recorded automatically. Simultaneously, their interactive behaviour was assessed by an independent observer via closed-circuit television. The following behaviours were analysed: aggressive postures, allogrooming, scratching, anxiety-related behaviours, social contact and self-grooming. Administration of diazepam at 1 and 3.5 mg/kg PO induced a significant (compared to control) reduction in scratching, aggressive behaviours, anxiety-related behaviours and an increase in allogrooming without affecting locomotor activity during confrontation. Differing responses dependant on gender were not found, nor did gender influence the effect of treatment on behaviour. Habituation to repeated confrontation did not occur. The results from this study demonstrate that this method can be used to measure anxiolytic activity in an objective manner.

Measuring anxiety in nonhuman primates: Effect of lorazepam on macaque scratching

Lorazepam (0.2 mg/kg IM) was given to group-living female macaques to assess the effect of anxiolytic treatment on scratching, a behavior pattern referred to as a displacement activity in the primate literature. Lorazepam selectively diminished scratching behavior. The drug effect was status-dependent: especially low-ranking animals showed a marked reduction in scratching. Lorazepam exerted a direct effect on scratching, that is the effect was not due to sedation or mediated by the influence of the drug on other behaviors. These results provide pharmacological validation to the ethological finding that scratching may be a manifestation of anxiety in monkeys. In addition, they suggest to use scratching as a behavioral measure in studies investigating nonhuman primate models of anxiety.

Stimulation of the nucleus paraventricularis thalami suppresses scratching and biting behaviour of arthritic rats and exerts a powerful effect on tests for acute pain

In 20 arthritis-sensitive Wistar rats, an electrode was implanted in the paraventricular thalamic nucleus (PV). In the tail-flick and hot-plate test, PV was stimulated continuously for a period of 30 min, during which every 5 min either a tail-flick or hot-plate test was performed. Stimulation of PV induced important prolongations of the reaction times on tail-flick and hot-plate tests. However, there was no significant correlation between the results of the two tests. The effect of stimulation was immediate and did not outlast the stimulation period. PV stimulation did not give rise to tolerance, either within the stimulation period of 30 min, or during the successive testing days. After the termination of these acute pain tests, rats were inoculated with Mycobacterium butyricum. All animals developed polyarthritis. PV stimulation had a profound suppressive effect on the scratching and biting behaviour displayed by the animals. This reduction in scratching and biting behaviour was specific for PV stimulation since stimulation of another target, the ventrolateral thalamic nucleus (4 animals), had no effect on these behaviours. The attenuation of the scratching and biting behaviour was not a result of a general motor impairment, since other behaviours increased (running and sniffing) or did not change. There was no significant correlation between the results of scratching behaviour with those of the tail-flick and hot-plate test.