A Model for Drying Control Cosolvent Selection for Spin-Coating Uniformity: The Thin Film Limit

Birnie, Dunbar P.

doi:10.1021/la401106z

Cited by 51 publications

(48 citation statements)

References 56 publications

(75 reference statements)

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“…On a spinning wafer, local variations in evaporation can lead to areas where the liquid layer is thicker and less concentrated. 16,17 If the surface tensions of the liquid and dissolved contaminant are not equal, then gradients develop on the free interface of the liquid.…”

Section: Resultsmentioning

confidence: 99%

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Extrand

Moon

Monson

2014

ECS J. Solid State Sci. Technol.

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In this work, we developed a mathematical model to quantify the translation of soluble contaminants from bulk liquid chemicals to the surface of wafers during spin coating. We tested various kinds of liquids, including those used in application of photo-resist as well as wafer cleaning and surface preparation. To validate the model, dilute polymer solutions with different concentrations were deposited onto spinning wafers, where they flowed outward and then evaporated. We used ellipsometry to determine the mass of contaminant left behind on the wafers. The levels of deposited contaminants increased with concentration in the bulk liquid and decreased with spin speed. The model well predicted the experimental data and thus allows for estimation of contaminant translation during spin coating.As the quest for smaller, faster and less expensive electronic devices marches on, circuitry in those devices is also shrinking and becoming more sensitive to particles, metals and other forms of contamination. While the semiconductor industry generally has done an excellent job of understanding the purity of the materials and chemicals used in fabricating electronic devices, how impurities translate from equipment, components and chemicals through fabrication processes and onto wafers is less clear.Spin coating is a common process that brings liquid chemicals into direct contact with wafers. It is used to apply photo-resist, to clean, etch and dry wafers, as well as to evaluate the cleanliness of liquid filters, fluid handling components and systems. Application of photoresist by spin coating has been carefully studied. 1-17 Previous work describes experiments and modeling of relatively concentrated polymer solutions where the solvent is an organic liquid with low surface tension and high boiling point. 2-7,10,11 However, liquids with a much broader range of properties are used in semiconductor processes and contaminants in those liquids are typically present at very low levels. Therefore, the aim of this work is to develop a mathematical model for quantifying the translation of low levels of soluble contaminants from liquids to wafers during spin coating and validate with experiments. TheoryTo quantify the translation of more dilute concentrations of soluble contaminants from bulk chemicals to the surface of wafers, a working model is needed. Consider the following scenario. A volatile liquid containing soluble, non-volatile contaminant is dispensed onto a wafer that is spinning at a constant rotational velocity of ω. Excess liquid is immediately flung from the spinning wafer. The remaining liquid layer flows outward under centrifugal force. We assume the contaminants simply move along with the liquid. Once outward flow of the spinning liquid layer slows and evaporation takes over, the contaminant is deposited onto the surface of the wafer.To construct our working equation, we begin with the classic analysis of liquid on a spinning disk by Emslie, Bonner and Peck. 1 Assume that the process is isothermal, the liquid is Newtonia...

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Section: Resultsmentioning

confidence: 99%

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Extrand

Moon

Monson

2014

ECS J. Solid State Sci. Technol.

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“…"Growth", on the other hand, refers to the diffusion and absorption of the molecules of the solute onto the surfaces of the existing nuclei, resulting in the cluster formation, cluster development, and aggregation. The nature of the solution, method of the deposition, the substrate roughness, and the properties of the solute greatly affect the crystallization mechanism in the molecular scale [42,43].…”

Section: Methodsmentioning

confidence: 99%

“…The average Avrami constant and exponent, K a and q, obtained from the TG measurements, are also listed in Table 1. Z 0 is interpreted as the number of attempts made by the nuclei in the unit of time to overcome the barrier energy [42,43]. Z 0 also represents the induction time of recognizable seed formation [2,45].…”

Section: Pristine Samples Svpt Samplesmentioning

confidence: 99%

“…Table 1 shows that the Avarmi exponent of the SVPT sample is larger than that of the pristine sample. According to the literature, q 1 is expected to be in the range of 1 to 3, where~1 usually represents the formation of the rode-like 1D structures,~2 is associated with the formation of planar or disc-like 2D structures or lateral growth, and~3 is associated with the spatially-expanded or 3D columnar crystals [43][44][45][46][47]. The value of q 2 which is typically in the range of 0 to 1 indicates the contribution of nucleation in the crystallization process.…”

Section: Pristine Samplesmentioning

confidence: 99%

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Effect of the Ultrasonic Substrate Vibration on Nucleation and Crystallization of PbI2 Crystals and Thin Films

Zabihi

Eslamian

2018

Crystals

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Preparation of defect-free and well-controlled solution-processed crystalline thin films is highly desirable for emerging technologies, such as perovskite solar cells. In this work, using PbI 2 as a model solution with a vast variety of applications, we demonstrate that the excitation of a liquid thin film by imposed ultrasonic vibration on the film substrate significantly affects the nucleation and crystallization kinetics of PbI 2 and the morphology of the resulting solid thin film. It is found that by applying ultrasonic vibration to PbI 2 solution spun onto an ITO substrate with a moderate power and excitation duration (5 W and 1 min for the 40 kHz transducer used in this study), the nucleation rate increases and the crystals transform from 2D or planar to epitaxial 3D columnar structures, resulting in the suppression of crystallization dewetting. The effects of various induced physical phenomena as a result of the excitation by ultrasonic vibration are discussed, including microstreaming and micromixing, increased heat transfer and local temperature, a change in the thermodynamic state of the solution, and a decrease in the supersaturation point. It is shown that the ultrasonic-assisted solution deposition of the PbI 2 thin films is controllable and reproducible, a process which is low-cost and in line with the large-scale fabrication of such solution-processed thin films.

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“…In many coating and printing applications, the liquid film contains more than one solvent. When a nonvolatile solvent is added to the film, gradients of this solvent concentration can induce solutal Marangoni flows which can affect the transport processes within the film . In the closely related case of drying droplets, some studies have suggested that solutal Marangoni flows can be exploited to create more uniform printed patterns and suppress the coffee‐ring effect.…”

Section: Evaporating Two‐solvent Film On a Heated Substrate: Solutal mentioning

confidence: 99%

Drying of multicomponent thin films on substrates with topography

Pham

Cheng

Kumar

2016

J Polym Sci B Polym Phys

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Drying of multicomponent thin liquid films is an important step in coating and printing processes. In many cases, the substrate on which the film rests may possess topography, either intended or unintended. We present a lubrication‐theory‐based model describing the fundamentals of drying on such substrates. The film consists of volatile solvent and additional nonvolatile components such as colloidal particles, surfactants, and nonvolatile solvents. A system of one‐dimensional partial differential equations accounting for the film height, depth‐averaged concentration of bulk nonvolatile components, and interfacial concentration of insoluble surfactant is derived. Evaporation is included using the well‐known one‐sided description, and the governing equations are solved with finite‐difference methods to study various limiting cases. The results highlight the influence of evaporation rate, and thermal, surfactant, and solutal Marangoni flows on the film thickness and colloidal particle distribution. We find that, in a realistic region of parameter space, the addition of a nonvolatile solvent yields a film that conforms to the substrate topography. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1681–1691

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A Model for Drying Control Cosolvent Selection for Spin-Coating Uniformity: The Thin Film Limit

Cited by 51 publications

References 56 publications

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Effect of the Ultrasonic Substrate Vibration on Nucleation and Crystallization of PbI2 Crystals and Thin Films

Drying of multicomponent thin films on substrates with topography

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