Role of interparticle forces during stress-induced agglomeration of CMP slurries

Chang, Feng-Chi; Kumar, Purushottam; Singh, Rohit; Balasundaram, Kannan; Lee, Jae-Seok; Lee, Jinhyung; Singh, Rajiv K.

doi:10.1016/j.colsurfa.2011.09.001

Cited by 18 publications

(6 citation statements)

References 13 publications

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“…4 shows. For this study, the reduction of copper MRR was observed, which matched well with Chang et al 22 It also postulated that too high ionic strength could cause agglomeration of silica particles in the slurry, resulting in a non-uniform contact between the particles and the wafer surface, which caused the lower MRR. On the other way, an excess of potassium ion can accelerate peroxide failure which will also reduce copper MRR.…”

Section: Resultssupporting

confidence: 89%

“…On the other way, an excess of potassium ion can accelerate peroxide failure which will also reduce copper MRR. 20,22 The influence of potassium ionic strength on TEOS removal rate.-TEOS is mainly composed of acidic oxides silica. During CMP, the TEOS surface may react with hydroxyl ions in the alkaline solution and form soluble silicate which will flow away with slurry.…”

Section: Resultsmentioning

confidence: 99%

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Improvement of Barrier CMP Performance with Alkaline Slurry: Role of Ionic Strength

Wang

Niu

Liu

et al. 2018

ECS J. Solid State Sci. Technol.

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With the development of ultra-large scale integrated circuits, chemical mechanical planarization (CMP) has been one of the most critical processes to achieve global planarization. The ionic strength of slurry is one of the key factors influencing the material removal rate and surface quality during CMP process. In this paper, potassium nitrate was used to enhance ionic strength in baseline slurry, and the removal mechanism of copper and TEOS (tetraethylorthosilicate) were investigated. The results showed that, when the potassium ionic strength was 100mM, TEOS and copper removal rate can reach 768Å/min and 395Å/min respectively, and the removal rate selectivity ratio was 1.98 which can match well with the industrial production requirement. On pattern wafer, after polishing 60s, the dishing and erosion were amended to be 570 ± 50Å and 195 ± 30Å respectively, and the number of total defects was about 9. Such results provide guiding significance for industrial production.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Improvement of Barrier CMP Performance with Alkaline Slurry: Role of Ionic Strength

Wang

Niu

Liu

et al. 2018

ECS J. Solid State Sci. Technol.

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“…33 That means that pH 11 is more conductive to lead to interparticle repulsive and prevent agglomeration according to the classic Derjaguin-Landau -Verwey -Overbeek (DLVO) theory. 34 However, it was found that pH variation would not only change the repulsive forces between particles, but also alter the solubility of the silica colloidal particles. When the pH is above 10.5, as shown in Figure 10, part of the silica colloids will dissolve.…”

Section: Inorganic Alkali Koh As Ph Regulatormentioning

confidence: 99%

Chemical Interactions and Mechanisms of Different pH Regulators on Copper and Cobalt Removal Rate of Copper Film CMP for GLSI

Zhou

Wang

Niu

et al. 2019

ECS J. Solid State Sci. Technol.

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As the feature size of integrated circuits (ICs) shrinks down to 14nm and below, Cobalt (Co) is identified as a suitable barrier layer material. Copper (Cu) has been widely used as the most basic interconnection metallic material for Giant-large scale integrated circuits (GLSI). A higher removal rate (RR) selectivity between Cu and Co is desired to obtain in copper film chemical mechanical polishing (CMP) because the traditional three-step polishing is replaced by two-step polishing of copper and barrier under lower technology nodes. The purpose of copper film polishing is to achieve effective removal of Cu and ultimately stop on the layer of Co. The pH value of slurry is a critical factor affecting the material removal rate and the stability of the slurry. The influence of different kinds of pH regulators and different pH values on the removal rates and the stability of slurries were investigated in this paper. Three pH regulators were chosen in the experiments, containing macromolecular chelating agent FA/OII as organic alkali, KOH as inorganic alkali and KOH mixed with a small amount of tetraethyl ammonium hydroxide (TEAH, C 8 H 21 NO) as mixed alkali. According to the investigation of removal rate results and stability experiments results, 10.5 was identified as a suitable pH value and a relatively higher removal rate selectivity was obtained. Meanwhile, using the mixed alkali to adjust slurry pH value can effectively increase the selectivity of Cu and Co and the stability of the copper slurry. The adsorption of TEAH on Cu and Co surface was considered as the critical reason relating to the slight removal rate decline, which was verified by XPS measurements.

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“…In some reports, Fenzhichang et al [6] showed that lowering pH or adding ionic salts would reduce the electrostatic repulsive force of SiO 2 colloids, leading to slurry agglomeration. Wonseopchoi et al [12] found that ionic salts would increase the removal rate of dielectric silica, and Jianchao Wang et al [14] found that potassium ion had a higher medium removal rate.…”

Section: Introductionmentioning

confidence: 99%

“…2. The slurry is caked by the shear stress of the pipe wall during transportation of the machine [5,6]. 3.…”

Section: Introductionmentioning

confidence: 99%

Methods and Mechanistic Analysis of Improving the Dispersion of Nano Silica Colloidal Particles in Chemical Mechanical Polishing Slurries

Zeng

Zhao

Liu

et al. 2021

Preprint

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The colloidal silica is usually used as the abrasive for the copper CMP polishing slurry in integrated circuit multilayer copper wiring. The aggregation of colloidal silica in the slurries tend to aggregate spontaneously, resulting in the continuous changes of the polishing effect, such as scratch defects, removal rate, etc. This situation can lead to the potential instability of the polishing slurry, which should be avoided in industrial production. In this paper, the aggregation and dispersion properties of polishing slurries were systematically studied, and an improved scheme was proposed to improve the dispersion of slurries to prevent agglomeration. These affecting factors including slurries’ pH, electrolyte additive (KNO3) and polyelectrolyte (PAA-Na) were assessed with LPC, Zeta potential and particle size. A better pH range for slurries was determined from the point of view of isoelectric point and dissolution of colloidal silica. And the dissolution of colloidal silica was verified by UV-vis experiment. Anionic surfactant (SDS), Cationic surfactant (DTAC) and Nonionic surfactant (AEO-15) was analyzed for their dispersion in slurries from the point of view of static electricity force and steric hindrance space force, and the synergistic mechanism of mixed SDS and AEO-15 on slurries dispersion was put forward. In addition, the effect of the improvement of slurry dispersion on reducing scratching defects on the surface of polished copper blanket was also tested in this paper.

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Role of interparticle forces during stress-induced agglomeration of CMP slurries

Cited by 18 publications

References 13 publications

Improvement of Barrier CMP Performance with Alkaline Slurry: Role of Ionic Strength

Improvement of Barrier CMP Performance with Alkaline Slurry: Role of Ionic Strength

Chemical Interactions and Mechanisms of Different pH Regulators on Copper and Cobalt Removal Rate of Copper Film CMP for GLSI

Methods and Mechanistic Analysis of Improving the Dispersion of Nano Silica Colloidal Particles in Chemical Mechanical Polishing Slurries

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