Role of polycation adsorption in poly-Si, SiO2 and Si3N4 removal during chemical mechanical polishing: Effect of polishing pad surface chemistry

Penta, Naresh K.; Matovu, John B.; Veera, P. R. Dandu; Krishnan, Sitaraman; Babu, S. V.

doi:10.1016/j.colsurfa.2011.07.039

Cited by 25 publications

(30 citation statements)

References 40 publications

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“…These results are also similar to those of Penta et al 22 and Trotter et al 36 who used a centrifugal washing method similar to ours and analyzed the total organic content in the supernatant.…”

Section: P39supporting

confidence: 81%

“…21,22 UV-vis spectra of the samples were measured in a quartz cuvette with an optical path length of 1 cm using a Perkin Elmer Lambda 35 UV-Vis spectrometer over the wavelength range of 430 to 580 nm. Spectral absorbance of aqueous solutions containing 5 ppm Eosin Y dye with and without 7.5 mM DADMAC were also measured for reference and used to compare with the spectral data of the supernatants.…”

Section: Methodsmentioning

confidence: 99%

“…UV-vis adsorption data.-The presence of DADMAC in the supernatants of centrifuged ceria and silica dispersions can be quantified using Eosin Y dye which shows a strong absorption peak at 516 nm 22 and whose intensity is lowered when it binds with DADMAC. For example, the absorption peak heights of an aqueous solution containing 5 ppm Eosin Y dye were ∼0.54 and ∼0.41 (arbitrary units) in the absence and presence of 7.5 mM DADMAC (Fig.…”

Section: P39mentioning

confidence: 99%

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Ceria-Based Slurries for Non-Prestonian Removal of Silicon Dioxide Films

Korkmaz

Babu

2014

ECS J. Solid State Sci. Technol.

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A slurry with a non-Prestonian dependence on the polishing pressure can help in minimizing dishing and erosion during shallow trench isolation chemical mechanical planarization. Here, we show that ceria-based slurries containing diallyldimethylammonium chloride (DADMAC) yield a non-Prestonian blanket film polish rate with a low threshold pressure (1-2 psi) when polishing plasma-enhanced chemical vapor (PECVD) tetraethylorthosilicate (TEOS) deposited oxide as well as thermal oxide films. The polishing mechanism of this non-Prestonian slurry was investigated by a series of experiments involving zeta potential measurements, thermogravimetric analysis (TGA) and UV-vis spectroscopy and it was shown that more DADMAC molecules are adsorbed on silica particles (as oxide film representatives) than on ceria particles and the binding strength between DADMAC and silica is much higher than that with ceria surface. Shallow trench isolation (STI) is an ubiquitous complimentary metal-oxide semiconductor isolation process technology. Deposition of an isolation stack that contains 3 to 10 nm thick 1,2 thermally grown pad oxide on top of a silicon substrate followed by the deposition of either plasma-enhanced chemical vapor deposition (PECVD) or low-pressure chemical vapor deposition (LPCVD) nitride layer (10 to 30 nm) 1 is the first step in the STI process. In the next step, active areas and isolation fields are determined by patterning the silicon nitride and silicon dioxide pad layers on the silicon substrate, followed by etching of trenches into the silicon substrate using the oxide/nitride stack as a mask. The trenches are then filled with oxide, employing high density plasma-enhanced chemical vapor deposition (PECVD) process using tetraethylorthosilicate (TEOS) as the source of silicon, because of its high gap-filling capacity. The deposited oxide not only fills the trenches but also generates an overfill, which needs to be removed. This is achieved through planarization of the oxide film topography by chemical mechanical planarization (CMP) using a slurry that produces a high oxide and very low nitride removal rates (RRs).In this STI process, major concerns include dishing within the oxide features resulting from over-polish as well as the erosion of the underlying nitride film and, in some cases, the details of the corner rounding near active areas. Therefore, optimization of the CMP process is crucial in order to achieve complete removal of the oxide on top of the nitride film with good planarity and uniformity and to avoid erosion and dishing during the CMP process. 3,4 One method that can be used to minimize dishing and erosion during STI CMP is to control the polishing performance by using a slurry that shows a non-Prestonian polishing behavior. Non-Prestonian behavior occurs when there is a non-linear relationship between applied polishing pressures and resulting polishing rates. Here we consider only the effect of pressure and not that of the rotational velocity on the blanket film polish rates.Several models were di...

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Section: P39supporting

confidence: 81%

Section: Methodsmentioning

confidence: 99%

Section: P39mentioning

confidence: 99%

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Ceria-Based Slurries for Non-Prestonian Removal of Silicon Dioxide Films

Korkmaz

Babu

2014

ECS J. Solid State Sci. Technol.

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“…Since it is well known that commercial ceria particles are available in a variety of forms and colors due to various impurities, we have chosen recently published results [2][3][4][5][6][7][8][9][10][11][12] in silicon dioxide CMP obtained using two types of ceria, one (d m ~180 nm) from Ferro Material Systems (see Table 1 below) and the other (d m ~60 nm) from Rhodia Inc. (Table 2) and different additives -amino acids, amines, carboxylic acids, and polymers. Both the particle size and pH influence these rates, but our focus here is only on understanding the chemical reactivity (the 'C' in CMP) of ceria abrasives in the presence of different additives in determining the silicon dioxide RRs.…”

Section: Resultsmentioning

confidence: 99%

“…There are also other applications [1] where both silicon dioxide and silicon nitride film removal rates need to be suppressed. To meet these variable requirements, several ceria-based formulations [2][3][4][5][6][7][8][9][10][11][12] containing a variety of additives (amino acids, amines, and polymers) were developed to selectively polish silicon dioxide and silicon nitride films and have been extensively used for many technologically important applications in silicon device manufacturing. Several of these dispersions suppress silicon nitride RRs to <2 nm/min [1][2][3][4]8] but not the oxide RR; a few do the reverse, [7] i.e., suppress silicon dioxide RRs to <2 nm/min, whereas others suppress both silicon dioxide and silicon nitride RRs to <2 nm/min [6].…”

Section: Introductionmentioning

confidence: 99%

The Role of Ce3+ vs. Ce4+ during the Polishing of Silicon Dioxide and Silicon Nitride Films using Ceria Abrasives

Dandu

Babu

2012

Imaging and Applied Optics Technical Papers

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Removal rate mechanisms of silicon dioxide and silicon nitride films during chemical mechanical polishing using ceria particles-based dispersion in the presence and absence of different additives are discussed. Our results show that ceria particles give high silicon dioxide and silicon nitride removal rates due to the reactivity of the Ce 3+ species with silicon dioxide or the sub-oxide formed on the silicon nitride surface by hydrolysis. With several additives, complete blockage of the reactive species and the reduction of oxide and nitride removal rates to <2 nm/min occur when the amount of the additive adsorbed has reached a limiting value. Silicon nitride removal rates can also be suppressed to <2 nm/min when the conversion of the nitride surface to suboxide is hindered due to the adsorption of additives on the nitride surface.

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Abrasive-free and ultra-low abrasive chemical mechanical polishing (CMP) processes

Penta¹

2016

Advances in Chemical Mechanical Planarization (CMP)

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Role of polycation adsorption in poly-Si, SiO2 and Si3N4 removal during chemical mechanical polishing: Effect of polishing pad surface chemistry

Cited by 25 publications

References 40 publications

Ceria-Based Slurries for Non-Prestonian Removal of Silicon Dioxide Films

Ceria-Based Slurries for Non-Prestonian Removal of Silicon Dioxide Films

The Role of Ce3+ vs. Ce4+ during the Polishing of Silicon Dioxide and Silicon Nitride Films using Ceria Abrasives

Abrasive-free and ultra-low abrasive chemical mechanical polishing (CMP) processes

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