Mixed abrasives slurry

Hegde S, Babu SV. Study of surface charge effects on oxide and nitride planarization using alumina/ceria mixed abrasive slurries. Electrochem Solid State Lett 2004 7(12) G316-G318. 

Seo Y, Lee W, Yeh P. Improvements of oxide chemical-mechanical polishing performances and aging effect of alumina and silica mixed abrasive slurries. Microelectr Eng 2004 75 361-366. 

Y. Seo, S. Park, W. Lee, Effects of manganese oxide—mixed abrasive slurry on the tetraethyl oithosiUcate oxide chemical mechanical polishing for planarization of interlayer dielectric film in the multilevel interconnection, J. Vac. Sd. Technol. A 26 (2006) 996-1001. 

JindaL S. Hegde, S.V. Babu, Evaluation of alumina/silica mixed abrasive slurries for chemical-mechanical pohshing of copper and tantalum, in Proceedings of the 18th Inti VLSI Multilevel Interconnection Conference, 2001, p. 297. 

Numerous researches have been conducted to modify abrasive particles for scratch reduction. Mixed abrasive slurry and various dispersants were used for the development of hne slurries [44,45] slurries made of abrasives with soft polymer coating are also proposed [46] polymer-core silica-shell composite abrasives were reported too [47]. However, most of these modified/composite abrasive slurries remain experimental and have not received wide industrial acceptance yet, because of challenges in particle control and difficulty in cleaning the residual abrasives. 

A. Jindal, S. Hegde, S.V. Babu, Chemical mechanical polishing using mixed abrasive slurries, Electrochem. Solid-State Lett. 5 (7) (2002) G48—G50. 

The principle of the shaking abrasion test is used to determine the water sensitivity of mixes for slurry surfacings consisting of 0/2 mm aggregate and cationic emulsion for slurry surfacing. 

Abrasive slurry system mixing of fluid medium and abrasive particles takes place prior to pressurization in a separate chamber to create the slurry. Higher wear rates throughout the equipment experienced using this system, but less expensive. 

Slurry Diluting or blending chemical Mix ratio by volume abrasive to part B... 

The most commonly used abrasives in CMP slurries are silica (Si02) and alumina (AI2O3). The physical appearance of these abrasives, before mixing with water, are white powders, as shown in Fig. 1. These materials must be ultrapure (>99.99%) and have nearly uniform particle shape and size to ensure a consistent and reasonable polish rate. 

A wide variety of catalytic materials are used as slurry-phase catalysts, most being metals supported on high surface area alumina, carbon, and silica (Fig. 2, label 3). Physical properties such as density are important since these catalysts must be suspended in the reaction mix. Since rapid agitation could lead to abrasion and attrition of the catalyst particles, strength is important. 

The slurry distribution and mixing system operates in the background of the actual wafer processing. However, a slurry with consistent physical and chemical properties is critical for maintaining a repeatable W CMP process with steady yield. Two of the most important parameters to monitor are etchant (oxidizer) and solid (abrasive particle) concentrations. 

Present results suggest that most of the silica slurry abrasives can be kept in dispersion by maintaining a RMFV value of 0.5ft/s, whereas alumina and ceria slurries require 1.5 to 2.5ft/s, depending on abrasive and chemical composition of the slurry. Next generation slurry delivery systems should be able to measure and control abrasive particle and chemical characteristics (to ensure mix accuracy and control of time sensitive components such as hydrogen peroxide, ammonium hydroxide, etc.) of the slurry on a real-time basis and consistently provide good slurry at the CMP tools. 

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