Mechanism of polishing of SiO2 films by CeO2 particles

Hoshino, Tetsuya; Kurata, Y.; Terasaki, Yuuki; Susa, K.

doi:10.1016/s0022-3093(01)00364-7

Cited by 292 publications

(159 citation statements)

References 12 publications

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“…Later, Sabia and Stevens 21 proposed that the polishing between the ceria abrasives and silicon dioxide is due to the reaction between the particles and the work surface, promoted by the presence of Ce 3+ on the abrasive surface. Later, Hoshino et al, 22 proposed a different model in which the Si-O-Si bonds react with hydroxylated ceria in water, forming Ce-O-Si bonds, and removing SiO 2 in the form of lumps (Figure 2b) rather than in the form of single molecules of Si(OH) 4 as proposed by Cook. 13 They supported this hypothesis using Fourier transform infra-red spectroscopy and inductively coupled plasma atomic emission spectroscopy analysis of the post polish slurry containing the material removed.…”

Section: Mechanismsmentioning

confidence: 99%

Shallow Trench Isolation Chemical Mechanical Planarization: A Review

Ramanathan

Dandu

Babu

2015

ECS J. Solid State Sci. Technol.

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Electrical isolation of the billion or so active components in each integrated device is achieved using shallow trench isolation (STI) which requires chemical mechanical planarization (CMP) involving silicon dioxide removal at a high rate and stopping on an underlying silicon nitride film. Several colloidal slurries with various additives can yield the desired high rate selectivity between the oxide and nitride films during CMP while maintaining an acceptably low nitride rate. Here, many of such high selectivity STI CMP slurries described in the literature are reviewed along with the characteristics of the colloidal dispersions like the abrasives, additives, the interactions between them and with the films being planarized and the associated pH range in which the high selectivity is observed. The mechanisms proposed to explain the high reactivity of ceria with oxide, the role of additives in suppressing the nitride removal rate and resulting high selectivity are discussed. Reduction of a multitude of defects in post-CMP processed STI structures still remains an important challenge, especially as the feature sizes continue to shrink. Chemical mechanical planarization (CMP) is one of the important enabling processes in facilitating multilevel metallization (in some cases reaching up to 14 levels) and incorporation of novel gate and channel materials at the component level in modern semiconductor device manufacturing where its use has become widespread and ubiquitous.1-6 Here, we review recent advances and remaining challenges in one specific application of CMP, the shallow trench isolation (STI) process. STI is a method of electrically isolating active areas using trenches created in the Si substrate around the active elements and filling it with an insulating dielectric, such as silicon dioxide or silicon oxy-nitride or silicon carbonitride.7-11 Process details of the STI structures are available in numerous publications. There are a multitude of techniques available for oxide deposition and even though the resulting oxides have very different properties, for simplicity we do not distinguish between them in this review. For completeness and ease of reference, a schematic representation of the STI process is given in Figure 1. While the trenches are being filled, silicon dioxide also deposits over unwanted areas on the entire wafer (since selective deposition in trenches only is not possible) creating an uneven topography. The excess and unwanted oxide has to be completely removed and CMP has proven to be the only viable and robust global and local planarization capable process technology.Here, as shown in Figure 1, presence of a very thin silicon nitride stop layer (deposited on another thin pad oxide layer to control film stress) is an essential and integral part of the process. This nitride stop layer prevents any damage during planarization to the all-important epitaxially grown surface underneath and is itself removed by a wet etch process subsequent to the overburden oxide removal. Since the integrity of the...

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Section: Mechanismsmentioning

confidence: 99%

Shallow Trench Isolation Chemical Mechanical Planarization: A Review

Ramanathan

Dandu

Babu

2015

ECS J. Solid State Sci. Technol.

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“…2) and Hoshino et al 19) showed that D 50 /µm was 1.689 and all particles were <5 µm. In addition, CeO 2 , which is the main component of polishing materials, had an average particle diameter of 80 nm, which did not change even after polishing.…”

Section: ¹1mentioning

confidence: 94%

Dissolution Behavior of La2O3, Pr2O3, Nd2O3, CaO and Al2O3 in Sulfuric Acid Solutions and Study of Cerium Recovery from Rare Earth Polishing Powder Waste via Two-Stage Sulfuric Acid Leaching

Hirato

2013

Mater. Trans.

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This study describes a hydrometallurgical process to investigate the cerium recovery from rare earth polishing powder waste (REPPW) containing main elements such as cerium, lanthanum, praseodymium, neodymium, calcium and aluminum. First, dissolution experiments on La 2 O 3 , Pr 2 O 3 , Nd 2 O 3 , CaO and Al 2 O 3 with 5 µm particle size in sulfuric acid solutions were carried out using a batch reactor with various acid concentrations (115 mol/dm 3 ) at different temperatures (30180°C). The effects of these two parameters on the dissolution reaction were studied. The obtained results showed that two sequential leaching steps were needed to separate cerium from the mixture of CeO 2 , La 2 O 3 , Pr 2 O 3 , Nd 2 O 3 , CaO and Al 2 O 3 . The total process for cerium recovery from REPPW via two-stage acid leaching was then developed through the collection of experimental results. Moreover, the dissolution rate of Al 2 O 3 was expressed by a shrinking core kinetics model. The variation of the dissolution rate constant with temperature obeyed the Arrhenius equation with activation energy of 130 kJ·mol ¹1 and reaction rate constant as a function of the acid concentration of C 0.41. On the basis of the above data, a k-T (reaction rate constant-reaction temperature) diagram for a CeO 2 Al 2 O 3 H 2 SO 4 H 2 O system that permits rational extraction of CeO 2 and Al 2 O 3 was devised.

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“…Similarly, the conventional polishing process itself can lead to the formation of damage sites. 9,10,11,12 Such damage sites result from both surface and subsurface mechanical damage that is inherent to the high normal loads associated with conventional lap polishing as illustrated in Figure 6. In addition to the mechanical damage itself, such surface and subsurface cracks can serve as sites that can trap optically absorbing species, such as iron, ceria, and other contaminants, which are typically present in the polishing process.…”

Section: Laser Resistant Large-aperture Opticsmentioning

confidence: 99%

Developing magnetorheological finishing (MRF) technology for the manufacture of large-aperture optics in megajoule class laser systems

Menapace

2010

SPIE Proceedings

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Over the last eight years we have been developing advanced MRF tools and techniques to manufacture meter-scale optics for use in Megajoule class laser systems. These systems call for optics having unique characteristics that can complicate their fabrication using conventional polishing methods. First, exposure to the high-power nanosecond and sub-nanosecond pulsed laser environment in the infrared (>27 J/cm 2 at 1053 nm), visible (>18 J/cm 2 at 527 nm), and ultraviolet (>10 J/cm 2 at 351 nm) demands ultra-precise control of optical figure and finish to avoid intensity modulation and scatter that can result in damage to the optics chain or system hardware. Second, the optics must be super-polished and virtually free of surface and subsurface flaws that can limit optic lifetime through laser-induced damage initiation and growth at the flaw sites, particularly at 351 nm. Lastly, ultra-precise optics for beam conditioning are required to control laser beam quality. These optics contain customized surface topographical structures that cannot be made using traditional fabrication processes. In this review, we will present the development and implementation of large-aperture MRF tools and techniques specifically designed to meet the demanding optical performance challenges required in largeaperture high-power laser systems. In particular, we will discuss the advances made by using MRF technology to expose and remove surface and subsurface flaws in optics during final polishing to yield optics with improve laser damage resistance, the novel application of MRF deterministic polishing to imprint complex topographical information and wavefront correction patterns onto optical surfaces, and our efforts to advance the technology to manufacture largeaperture damage resistant optics.

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Mechanism of polishing of SiO2 films by CeO2 particles

Cited by 292 publications

References 12 publications

Shallow Trench Isolation Chemical Mechanical Planarization: A Review

Shallow Trench Isolation Chemical Mechanical Planarization: A Review

Dissolution Behavior of La<sub>2</sub>O<sub>3</sub>, Pr<sub>2</sub>O<sub>3</sub>, Nd<sub>2</sub>O<sub>3</sub>, CaO and Al<sub>2</sub>O<sub>3</sub> in Sulfuric Acid Solutions and Study of Cerium Recovery from Rare Earth Polishing Powder Waste via Two-Stage Sulfuric Acid Leaching

Developing magnetorheological finishing (MRF) technology for the manufacture of large-aperture optics in megajoule class laser systems

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