Effects of Ceria Abrasive Particle Size Distribution below Wafer Surface on In-Wafer Uniformity during Chemical Mechanical Polishing Processing

Kim, Hojoong; Yang, Ji Chul; Kim, Myungjoon; Oh, Dong-won; Lee, Chilgee; Kim, Sang-Yong; Kim, Taesung

doi:10.1149/1.3562559

Cited by 6 publications

(6 citation statements)

References 20 publications

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“…Some studies have examined the effect of the slurry's PSD on scratches either by spiking the slurry with larger particles [14][15][16] or by changing the overall PSD. 17,18 However, these studies focused on a regime where the load/ particle exceeded the initiation load for fracture (typically >0.1 N) leading to brittle fracture.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, little effort has been devoted to quantitatively understanding and predicting the surface roughness and texture of the workpiece as a function of the PSD and pad properties. Some studies have examined the effect of the slurry's PSD on scratches either by spiking the slurry with larger particles or by changing the overall PSD . However, these studies focused on a regime where the load/particle exceeded the initiation load for fracture (typically >0.1 N) leading to brittle fracture.…”

Section: Introductionmentioning

confidence: 99%

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Microscopic Removal Function and the Relationship Between Slurry Particle Size Distribution and Workpiece Roughness During Pad Polishing

et al. 2013

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Various ceria and colloidal silica polishing slurries were used to polish fused silica glass workpieces on a polyurethane pad. Characterization of the slurries' particle size distribution (PSD) (using both ensemble light scattering and single particle counting techniques) and of the polished workpiece surface (using atomic force microscopy) was performed. The results show the final workpiece surface roughness is quantitatively correlated with the logarithmic slope of the distribution function for the largest particles at the exponential tail end of the PSD. Using the measured PSD, fraction of pad area making contact, and mechanical properties of the workpiece, slurry, and pad as input parameters, an Ensemble Hertzian Gap (EHG) polishing model was formulated to estimate each particle's penetration, load, and contact zone. The model is based on multiple Hertzian contact of slurry particles at the workpiece-pad interface in which the effective interface gap is determined through an elastic load balance. Separately, ceria particle static contact and single pass sliding experiments were performed showing~1-nm depth removal per pass (i.e., a plastic type removal). Also, nanoindentation measurements on fused silica were made to estimate the critical load at which plastic type removal starts to occur (P crit~5 3 10 À5 N). Next the EHG model was extended to create simulated polished surfaces using the Monte Carlo method where each particle (with the calculated characteristics described above) slides and removes material from the silica surface in random directions. The polishing simulation utilized a constant depth removal mechanism (i.e., not scaling with particle size) of the elastic deformation zone cross section between the particle and silica surface, which was either 0.04 nm (for chemical removal) at low loads (

P crit ). The simulated surfaces quantitatively compare well with the measured rms roughness, power spectra, surface texture, absolute thickness material removal rate, and load dependence of removal rate.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microscopic Removal Function and the Relationship Between Slurry Particle Size Distribution and Workpiece Roughness During Pad Polishing

et al. 2013

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“…Ceria nanoparticles has received much attention in recent years due to its potential applications in several fields including memory devices, fuel cell reformer applications, UV absorption block, gas sensors, three way catalyst (TWC) in automobiles, and polishing materials [1][2][3][4][5][6][7] . Furthermore, rare earth doped ceria is a promising electrolyte and anodic component material in solid oxide fuel cells (SOFC) owing to its high oxygen storage capacity 8 , ionic conductivity 5,9 and high thermal stability 10 .…”

Section: Introductionmentioning

confidence: 99%

Ceria Nanoparticles Synthesized by a Polymer Precursor Method

Soni

Biswas

2013

Int. J. Mod. Phys. Conf. Ser.

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We report a novel synthesis technique of ceria nanoparticles by a sol-gel type chemical process using poly-vinyl alcohol (PVA) as a capping as well as a reducing agent. The as-synthesized CeO 2 nanoparticles were characterized by X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). The XRD analysis reveals the fluorite type face centered cubic structure in the ceria nanoparticles with an average crystallite size of 6 nm and 9 nm for the samples calcined at 350°C and 400°C, respectively.

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“…10 With respect to the effect of PAA on abrasive particles, our group previously reported influence of PAA molecules on the transport of ceria particles. 11 Regarding the mechanical aspect of CMP, researchers focused on the contact configuration among pad, slurry and wafer. 12 The coefficient of friction (COF) during CMP can provide useful information on the contact area, micro-scratch occurrence, and other mechanical attributes.…”

mentioning

confidence: 99%

Frictional Characteristic of Polymeric Additive for the Slurry of Chemical Mechanical Planarization Process

Kim

Yang

Lee

et al. 2012

ECS J. Solid State Sci. Technol.

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In this study, we analyzed the coefficient of friction (COF) of film surface and pad interface during the wafer polishing process to make a correlation with the existence of polyelectrolyte additive in the slurry, which is adsorbed onto the wafer surface. The poly-acrylic acid (PAA) polymer was added to the slurry in this study because of its proven effect on SiO2 (Oxide)/Si3N4 (Nitride) removal selectivity. Different contact conditions between the wafer surface and the slurry with PAA were established for various PAA concentrations and slurry pHs in polishing experiments. The COF was increased with the adsorption amount of PAA on the wafer surface whereas the dissolved PAA in the slurry served as lubricant that lowered the COF. The lateral force microscope (LFM) with a pad debris particle attached tip, which simulates single asperity contact, confirmed the COF result in a wafer scale experiment. Finally, the direct measurement of absorbed PAA by atomic force microscopy (AFM) in aqueous condition revealed that COF increased with changes of surface morphology and roughness.

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Effects of Ceria Abrasive Particle Size Distribution below Wafer Surface on In-Wafer Uniformity during Chemical Mechanical Polishing Processing

Cited by 6 publications

References 20 publications

Microscopic Removal Function and the Relationship Between Slurry Particle Size Distribution and Workpiece Roughness During Pad Polishing

Microscopic Removal Function and the Relationship Between Slurry Particle Size Distribution and Workpiece Roughness During Pad Polishing

Ceria Nanoparticles Synthesized by a Polymer Precursor Method

Frictional Characteristic of Polymeric Additive for the Slurry of Chemical Mechanical Planarization Process

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