The Effect of Frictional and Adhesion Forces Attributed to Slurry Particles on the Surface Quality of Polished Copper

Hong, Yi-Koan; Han, Ja-Hyung; Kim, Tae-Gon; Park, Jin-Goo; Busnaina, Ahmed

doi:10.1149/1.2393051

Cited by 19 publications

(12 citation statements)

References 14 publications

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“…Nowadays, research has been performed by controlling the sign of zeta potential to meet this need. But all these are qualitative results . The quantitative relationship between particle adsorption and zeta potential has not been reported.…”

Section: Introductionmentioning

confidence: 99%

The quantitative description between zeta potential and fluorescent particle adsorption on Cu surface

Mei

2013

Surface & Interface Analysis

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The influence factor for polystyrene based fluorescent particles' adsorption on Cu surface in liquid environment was investigated. The fluorescent particles with a size of 100 nm were used as the adsorbing particle for avoiding the disturbance to the adsorption result. The contrast between the fluorescent image and SEM image showed that there was a one‐to‐one correspondence between the fluorescent spot and the particle. This revealed the method of counting the fluorescent spot to obtain the adsorbing particle result is accurate. Zeta potential and ionic strength would affect the value of electrical double layer force. And the electrical double layer force and Van der Waals force between particles and surface determined the behavior of particles when particles got close to Cu surface. Results showed that particle adsorption on Cu surface was linear to the multiply of zeta potential for particles and Cu surface. Also, the influence of ionic strength on fluorescent particle adsorption was investigated. Finally, the quantitative description between zeta potential, ionic strength and particle adsorption was given. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

The quantitative description between zeta potential and fluorescent particle adsorption on Cu surface

Mei

2013

Surface & Interface Analysis

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“…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.…”

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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“…16.27 [66]. The smallest adhesion force, 0.38 nN, was observed between the copper surface and alumina particles in a citric acid solution at pH 6.…”

Section: Adhesion Force Of Silica and Alumina On Cumentioning

confidence: 91%

“…By using AFM, one can image the surface in atomic resolution and measure the interaction force at nN scale. The force versus distance (F versus D) curves can be used to measure the vertical force that the tip applies on the surface while a contact AFM image is being taken [66][67][68]. In practice, F versus D curves can be quite complex and the conclusions based on these curves may be applicable only to the system under study.…”

Section: Adhesion Force Of Silica and Alumina On Cumentioning

confidence: 99%

Post‐CMP Cleaning

Park

Kim

2007

Microelectronic Applications of Chemical Mechanical Planarization

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With the decrease in device feature sizes, planarization of both front-and back-end layers by the chemical-mechanical planarization (CMP) process has become necessary for integrated circuit (IC) fabrication technologies smaller than 0.35 mm. As much as the industry has benefitted tremendously from the introduction and implementation of CMP, the very process has also brought along a set of new challenges to the fabs. For example, surface defects or imperfections such as leftover particles, organic residues, metallic contaminations, scratches, and corrosion spots can often be found on the polished wafers after the CMP process. These CMP-induced defects can arise from the slurries, the polishing pad, the pad conditioner, and to a lesser extent, the polisher. The leftover particles can physically attach to the wafer surface or, in the worst case, even partially embed into the top layer of a wafer. The CMP process can also leave metallic contamination typically in the range of 10 11 -10 12 atoms/ cm 2 . These contaminants mainly arise from the abraded metal lines, metal ions in the slurries, and polishers. In front-end applications such as a shallow trench isolation (STI) process, the control of metallic contamination levels is very critical because the following high-temperature process may lead to a complete incorporation of the metal ions into the lattice. In the case of back-end processes, if not removed, these metal contaminants can lower the breakdown voltage of devices. Also, fast diffusers such as copper can reach the active area from the backside surface or edge during the following thermal process [1]. During CMP, slurry additives and pad debris can leave organic residues on the Microelectronic Applications of Chemical Mechanical Planarization, Edited by Yuzhuo Li

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The Effect of Frictional and Adhesion Forces Attributed to Slurry Particles on the Surface Quality of Polished Copper

Cited by 19 publications

References 14 publications

The quantitative description between zeta potential and fluorescent particle adsorption on Cu surface

The quantitative description between zeta potential and fluorescent particle adsorption on Cu surface

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

Post‐CMP Cleaning

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