The Adsorption Behaviors of Citric Acid on Abrasive Particles in Cu CMP Slurry

Kang, Young‐Sun; Hong, Yi-Koan; Song, Jae-Hoon; Kim, In‐Kwon; Park, Jin-Goo

doi:10.1557/proc-867-w7.5

Cited by 3 publications

(1 citation statement)

References 3 publications

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“…[27][28][29][30][31][32][33][34][35][36][37][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. 43 The slurry pH and zeta potentials of particles and wafer surface could significantly affect the polishing performance.…”

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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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A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

Chen

2015

ECS J. Solid State Sci. Technol.

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Effects of Surface Forces on Material Removal Rate in Chemical Mechanical Planarization

Bozkaya

Müftü

2010

J. Electrochem. Soc.

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In chemical mechanical planarization, abrasive particles are pushed onto a wafer by a deformable pad. In addition to the pad-particle contact force, surface forces also act between the wafer and the particles. Experimental studies indicate the significance of slurry pH and particle size on the material removal rate ͑MRR͒. In this work, a model for MRR, including the contact mechanics of multiple particles caught in the interface of a rough, porous, and deformable pad and a rigid wafer, including the influences of van der Waals and double-layer forces, is introduced. The effects of surface forces on MRR were investigated for different applied pressures, pad elastic moduli, particle sizes, molar concentrations of ions, and zeta potentials of the wafer and particles. The attractive van der Waals forces increase the MRR, while the double-layer forces, calculated to be repulsive, lower the MRR. The relative magnitude of surface forces compared to the pad-particle force increases with a smaller particle size and a pad elastic modulus. The experimental trends for the variation in MRR with slurry pH were predicted well by the model when the variation in the zeta potential of the wafer and particles with respect to slurry pH is considered.

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Mechanics of the pad-abrasive-wafer contact in chemical mechanical polishing

Bozkaya¹

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The Adsorption Behaviors of Citric Acid on Abrasive Particles in Cu CMP Slurry

Cited by 3 publications

References 3 publications

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

Effects of Surface Forces on Material Removal Rate in Chemical Mechanical Planarization

Mechanics of the pad-abrasive-wafer contact in chemical mechanical polishing

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