Modelling tool for chemical-mechanical polishing design and evaluation

Runnels, Scott R.; Kim, I.; Schleuter, J.; Karlsrud, Chris; Desai, Maitri

doi:10.1109/66.705385

Cited by 37 publications

(21 citation statements)

References 10 publications

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“…The waferparticle contact force f w consists of the force transmitted through the pad-particle contact L p and surface forces between the wafer and the particle, including the vdW f vdw and electrical DL forces F ψ s− p with constant surface charge for a spherical particle and a plane surface: + e −κL [19] where E pad and υ pad are the Young modulus of the asperity and the Poisson ratio of the pad, respectively. A wsp is the effective Hamaker constant, ε r is the relative dielectric constant, ε 0 is the dielectric permittivity of vacuum, κ −1 is the double layer thickness and L is the distance of minimum approach.…”

Section: Modelingmentioning

confidence: 99%

“…Moreover, the mixed lubrication model taking into account the compressibility of the pad and the mold of slurry delivery 17,18 is used to give reasonable predictions of the pressure profiles and removal rates. 4,19,20 In order to capture the chemical behavior and describe the repetitive removal process of the wafer profile, the surface kinetics model is introduced to relate the overall polish rate to various kinetic processes occurring at the surface modulated by the mechanical parameters.4,21-26 Slurry chemicals which contain oxidizers, inhibitors and other additives in the slurry determining the reaction kinetics play an important role for the passivation of the wafer surface.27-38 The overall MRR is influenced by the existence of different compositions on the wafer surface, 31,34 resulting in the change of the wafer surface hardness, which affects the aggregate wear rate of the wafer material. 30,34,35,37 In addition to the effect on the wafer hardness, slurry chemicals have also been shown to influence the zeta potential of abrasive particles and the wafer, 27,29,35,[39][40][41][42] where the slurry pH was the primary factor affecting the zeta potentials.…”

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confidence: 99%

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A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

Chen

2015

ECS J. Solid State Sci. Technol.

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In this work, a new aluminum gate chemical mechanical planarization (CMP) model for material removal rate (MRR) is proposed in high-k metal gate (HKMG) process. Using the basic principles of steady-state oxidation reaction and mechanical abrasion mechanism, the combinational interaction of chemical and mechanical coupled effects on MRR was systematically described by process parameters, pad properties and concentration of oxidizer, and then balanced to construct an overall polishing rate. Because of the great significance of the slurry pH on MRR in CMP process, the effects of surface forces, including the influences of van der Waals (vdW) and double-layer (DL) forces simultaneously acted between the wafer and the particles were investigated. Meanwhile, the influence of particle sizes, abrasive loadings and zeta potentials of the wafer and particles on MRR was also analyzed. It is found that the attractive vdW forces strengthen the MRR, while the DL forces, calculated to be repulsive, lower the MRR. The magnitude of surface forces increases with a smaller particle size compared with the pad-particle force. When zeta potentials of the wafer and particles are considered as a function of slurry pH, the experimental trends for the MRR with slurry pH, applied pressure and abrasive loading were predicted well by the present model. Therefore, the governing equation of aluminum removal reveals some insights into the HKMG CMP process and can be utilized for optimizing and controlling the polishing rate of aluminum gate structures and performing sensitivity analyses of operating parameters. With the steady shrinkage of the feature size and device geometry of modern integrated circuits (ICs), chemical mechanical planarization (CMP) has become the most important process choice for the surface planarization in the fabrication of advanced multilever ICs in microelectronic industry.1 A variety of materials and structures, including copper damascene metallization, oxides in shallow trench isolation (STI) and inter-level dielectrics (ILD), replacement metal gate for high-k metal gate (HKMG) structures and fin field effect transistor (FinFET) devices are polished with different slurries. [2][3][4] In CMP process, a rotating wafer with different types of design structures is pushed against a rotating polishing pad which is immersed in slurries containing chemicals and abrasive particles. Pattern structures on the wafer surface are first chemically passivated by slurry chemicals and then removed by effects of contact interactions of abrasive particles which are trapped between the pad and the wafer. The contact mechanism of the particles in the slurry provides the opportunity to remove the material from the wafer surface at an acceptable production rate. 5The material removal rate (MRR) which has been studied extensively from both a modeling and experimental standpoint depends sensitively on pattern geometry, process parameters, chemical reactions, pad properties and mechanical abrasion. If the CMP process is not properly controlled...

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Section: Modelingmentioning

confidence: 99%

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confidence: 99%

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

Chen

2015

ECS J. Solid State Sci. Technol.

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“…The early ultrasonic machining mostly relies on the ultrasonic vibration of the http://dx.doi.org/10.1016/j.ultras.2014. 10.006 0041-624X/Ó 2014 Elsevier B.V. All rights reserved. instrument which makes the suspending abrasive particles gain sufficient energy to impact the polishing object aiming at removing the rougher part of the surface.…”

Section: Introductionmentioning

confidence: 98%

“…With the development of semiconductor technology, it has been accepted wildly [2], and as the rising of ultra large scale integration chips in recent years, it gains ever increasing attentions [3] and appears to be the only available method for global planarization [4,5]. In order to widen the application area and lower the manufacturing cost of chemical-mechanical polishing, many scholars have made efforts to research this polishing technology experimentally and theoretically [6][7][8][9][10][11], to date, it is also the point at issue [4,12].…”

Section: Introductionmentioning

confidence: 99%

Contribution of ultrasonic traveling wave to chemical–mechanical polishing

Li¹,

He²,

Zheng³

et al. 2015

Ultrasonics

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“…Under a certain polishing condition, Preston coefficient is assumed to be constant in the entire optic/pad interface. Numerous researches have revealed that a uniform distribution of relative velocity can be obtained through the rotations of the optic and the platen at the same speed [17,18]. Therefore, the surface figure, to a great extent, depends on the variation of the pressure distribution on the optic surface [19].…”

Section: Introductionmentioning

confidence: 99%

Deterministic measurement and correction of the pad shape in full-aperture polishing processes

Liao¹,

Zhang²,

Xie³

et al. 2015

J. Eur. Opt. Soc.-Rapid Publ.

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Full-aperture polishing is a significant process in fabricating large optical flats because it restrains Mid-Spatial Frequency errors and removes material quickly on the whole optic surface. Nevertheless, optical flats fabricated by full-aperture polishing generally fail to meet the stringent requirement of surface figure, which has to be corrected by sub-aperture polishing processes. Surface figure of optical flats in full-aperture polishing processes is primarily dependent on the pressure distribution uniformity which correlates intensively with the lap shape. At present, practical and precise means are urgently desired for measuring and correcting the lap shape, especially the polyurethane pad lap. In the study, we present a novel method for deterministic measurement of the pad shape. The method obtains the height of the pad at spirally distributed locations implemented by the revolution of the pad and translation of the laser displacement sensor. The pad shape in terms of matrixes whose elements representing the heights at the corresponding locations is then calculated by interpolation algorithm based on the obtained data. Further, we propose a method for deterministic correction of the pad shape utilizing a small conditioning tool. The dwell time algorithm and implementation strategy for the dwell time are provided for common full-aperture polishers. These solutions for the deterministic measurement and correction of the pad shape have been validated on a full-aperture polisher with polyurethane pad. The polishing experiments revealed that the optic surface figure was obviously improved.

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Modelling tool for chemical-mechanical polishing design and evaluation

Cited by 37 publications

References 10 publications

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

Contribution of ultrasonic traveling wave to chemical–mechanical polishing

Deterministic measurement and correction of the pad shape in full-aperture polishing processes

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