Model spin coating process

Several detailed analyses of the spin coating process have been conducted (Bornside et al., 1989 Emslie et al., 1958 Meyerhofer, 1978 Yonkoski and Soane, 1992). The analyses conducted by these authors have been shown to hold for a variety of volatile organic solvents (Birnie, 1997 Paul et al., 1996). However, this model may not apply well to spin coating in C02 because coatings from C02 are formed under drastically different conditions. This difficulty in relating the conventional process to C02-based spin coating is illustrative of the hurdles encountered when developing new processes in C02. 

Sahu, N., Parija, B., and Panigrahi, S. (2009) Fundamental understanding and modeling of spin coating process a review. Indian J. Phys., 83 (4), 493 - 502. 

Understanding the film formation process is critical to determining the outcome of the entire lithographic process. The need has been intensified in recent years as device features shrink to submicron sizes. Resist film uniformity must be held within a small tolerance to minimize exposure artifacts. Currently, achievement of this requirement demands a significant amount of time and effort to characterize a new resist material so that a viable spin-coating process can be established. Appreciable reduction of this effort could be attained if a quantitative model were available to describe the fluid behavior during spin coating. 

Previous attempts to model the spin coating process have relied on several major simplifying assumptions. Most treatments... 

Figure 25.13 Graphical representation of (a) Emslie, Bonner and Peck, (b) Meyerhofer, and (c) Cregan and O Brien models for the spin coating process.

The film formation in fhe spin-coating process for the polymer/fuller-ene blend system in the mixture solvent is a complex process because it is a nonequilibrium state that both thermodynamic and kinetic parameters can influence phase separation, and the system contains four components with dissimilar physical/chemical properties. We found the donor/acceptor components in the active layer can phase separate into an optimum morphology during the spin-coating process with the additive. Supported by AFM, TEM, and X-ray photoelectron spectroscopy (XPS) results, a model as well as a selection rule for the additive solvent, and identified relevant parameters for the additive are proposed. The model is further validated by discovering other two additives to show the ability to improve polymer solar cell performance as well. 

Here we have proposed a modified Cassie-Baxter model to investigate the influence of prirticle size on superhydrophobic behavior of sfiica nanosphere arrays. An assembly technique enabled to prepare well-ordered silica nanosphere arrays, and then the silica arrays were fluorinated by a spin-coating process. Compared with a F-coated flat surface, the contact angle on fluorinated silica nanoarrays reached a value of 152 1.4°. A Cassie-Baxter parameter, surface firaction (4>s), was used to simulate the hydrophobicity. It was found that the nanosphere size played an important role in affecting the hydrophobicity of the sphere arrays. The present work demonstrates that the superhydrophobicity of nanoarrays is well correlated with the modified Cassie-Baxter model. 

Figure 7.4 A schematic model describing the owing to solvent evaporation only. The interface film formation during the spin coating process, between the polymers destabilizes (iv) and the After the initial spin-off stage where both film phase separates laterally (v, vi).

Thin solid films of polymeric materials used in various microelectronic applications are usually commercially produced the spin coating deposition (SCD) process. This paper reports on a comprehensive theoretical study of the fundamental physical mechanisms of polymer thin film formation onto substrates by the SCD process. A mathematical model was used to predict the film thickness and film thickness uniformity as well as the effects of rheological properties, solvent evaporation, substrate surface topography and planarization phenomena. A theoretical expression is shown to provide a universal dimensionless correlation of dry film thickness data in terms of initial viscosity, angular speed, initial volume dispensed, time and two solvent evaporation parameters. 

Infrared spectra were recorded on a Perkin-Elmer Model 983G double-beam spectrophotometer in the transmission mode using 3500 A thick PBTMSS films spin-coated and processed on polished NaCl plates. Spectral subtraction and absorbance correction to account for the decreased film thickness were used to isolate the silicon oxide absorption band at about... 

Spin coating is a commonly available process in the IC industry and has been characterized and modeled for a variety of polymer solutions (16). The thickness of spin coated PI films depends... 

A model Phillips catalyst for ethylene polymerization has been prepared by spin coating of a Cr(III) precursor (Cr(acac)3) on a flat silicon wafer (100) covered by amorphous silica. The spin coating parameters were chosen in order to obtain a homogeneous film. The model catalyst was submitted to an activation process. The surface concentration of Cr decreased from about 0.8 to 0.4 Cr atom/nm as the temperature increased from 150 to 550°C. Direct information concerning the surface molecular species and the environment of Cr was provided by ToF-SIMS and XPS. At 350°C, the catalyst precursor was decomposed Cr species were in the form oxide and surface-anchored chromates. Upon final activation at 650°C for 6 h, Cr species were below the XPS detection limit however the model catalyst was active for ethylene polymerization at 160°C and 2 bar pressure. 

In this work, a Phillips model catalyst was prepared by spin coating of a THF solution of Cr(acac)3 on an oxidized silicon wafer. This study was mostly focused on a molecular description of the activation process in conditions similar to those used for industrial catalysts. This model catalyst was characterized by means of SEM, ToF-SIMS and XPS, and tested for ethylene pofymerization. 

An active Phillips model catalyst has been successfully prepared starting from a Cr(III) precursor. The active phase was deposited homogeneously on a silicon wafer by spin coating, and the model was submitted to the activation process usually applied to real Phillips catalysts. Using complementary surface science techniques, molecular information on the modifications of the state of the Cr during activation was provided. 

Bornside et al. [138] have developed a model for spin coating in which evaporation has been analyzed in terms of the mass flux (or mass transfer) from the liquid phase into the adjacent gas phase. Such a mass flux is controlled by a convection-diffusion process that depends on the solution concentration that increases as the solvent leaves the liquid phase. The characteristics of the gas phase in the close vicinity may also have a speciflc effect on the evaporation process. A modifled model based on the equations of Meyerhofer and Bornside was used by Chang et al. [123] to predict the fllm thickness of spin-coated polymers. In their model, two equations were used one to predict the wet fllm thickness, h, after spin coating but before drying and another to determine the final fllm thickness (hf). The film thicknesses that they have theoretically predicted agree well with those experimentally determined, especially in solutions of low polymer concentration. 

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