Effect of pH and Ionic Strength on Chemical Mechanical Polishing of Tantalum

Ramarajan, S.; Li, Y.; Hariharaputhiran, M.; Her, Yie-Shein; Babu, S. V.

doi:10.1149/1.1391010

Cited by 46 publications

(32 citation statements)

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“…Adding 0.25 wt% K 2 SO 4 , the oxide RRs increased throughout the pH range, presumably due to the increase in ionic strength. Several studies [19][20][21][22][23] have already shown that increasing the ionic strength increases oxide RRs due to the reduction in the electrostatic repulsion, an argument also supported by the potential data for the silica dispersions (later shown in Fig. 4).…”

Section: Resultssupporting

confidence: 60%

Use of anionic surfactants for selective polishing of silicon dioxide over silicon nitride films using colloidal silica-based slurries

Penta

Amanapu

Peethala

et al. 2013

Applied Surface Science

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Section: Resultssupporting

confidence: 60%

Use of anionic surfactants for selective polishing of silicon dioxide over silicon nitride films using colloidal silica-based slurries

Penta

Amanapu

Peethala

et al. 2013

Applied Surface Science

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“…Studies of surfactant adsorption have typically focused on conditions where there is clear electrostatic driving force for adsorption; i.e., where surfactants have opposite charge to those of metal oxide surfaces [22]. Ramarajan et al demonstrated CMP with high ionic strength slurries at high pH due to the reduction of electrostatic repulsion force [23]. The effects of alkaline ionic salts (KCl, LiCl and NaCl) on SiO 2 CMP using 500 nm diameter abrasive silica particles are reported by Choi et al [24].…”

Section: Introductionmentioning

confidence: 99%

Effect of surfactant and electrolyte on surface modification of c-plane GaN substrate using chemical mechanical planarization (CMP) process

Asghar

Qasim

Nelabhotla

et al. 2016

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…The electrical double-layer (DL) forces between the wafer and the abrasive particles depend on the zeta potentials of both the wafer and particles, and were shown to have a strong influence on the MRR. 35,[44][45][46][47] When the DL forces are attractive, the contact force between the wafer and abrasives becomes large, which causes the MRR for each abrasive particle to increase. 29,47 The experimentally observed variation in MRR with a slurry pH was attributed to the effect of a slurry pH on the zeta potential, which influences the magnitude of DL forces.…”

mentioning

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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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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Effect of pH and Ionic Strength on Chemical Mechanical Polishing of Tantalum

Cited by 46 publications

References 0 publications

Use of anionic surfactants for selective polishing of silicon dioxide over silicon nitride films using colloidal silica-based slurries

Use of anionic surfactants for selective polishing of silicon dioxide over silicon nitride films using colloidal silica-based slurries

Effect of surfactant and electrolyte on surface modification of c-plane GaN substrate using chemical mechanical planarization (CMP) process

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

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