The Removal of Airborne Molecular Contamination in Cleanroom Using PTFE and Chemical Filters

Yeh, Ching-Fa; Hsiao, Chih-Wen; Lin, Shiuan-Jeng; Hsieh, Chih-Min; Kusumi, Toshio; Aomi, H.; Kaneko, Hidehiro; Dai, Bau–Tong; Tsai, Ming-Shih

doi:10.1109/tsm.2004.826957

Cited by 29 publications

(20 citation statements)

References 5 publications

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“…It indicates the probability of a molecule to be adsorbed on the surface after contact. The sticking coefficient can be calculated by the following formula [1]: (4) where is vertical laminar flow velocity . By measuring the time-dependent surface density and ambient concentration , the kinetic parameters such as adsorption and desorption rate constants can be established from (2) using a numerical algorithm based on the least-squares error method.…”

Section: Surface Kinetics and Sticking Coefficientmentioning

confidence: 99%

“…Due to higher gas diffusivities, the surface arrival rate for inorganic gas phase species may greatly exceed those of particles with typical size of 0.01 to [3]. The use Manuscript of enclosures equipped with chemically-specific air filters and efficient purging of wafer boxes with inert gas are currently being used to reduce the level of contamination in sensitive production areas [4], [5]. Therefore, the strong needs to detect ever-shrinking critical defects have been reflected in the technical specification of Semiconductor Equipment and Materials International (SEMI) to recommend maximum allowable concentrations of airborne molecular contaminants [6].…”

Section: Introductionmentioning

confidence: 99%

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Surface Deposition of Ionic Contaminants on Silicon Wafers in a Cleanroom Environment

Lin

Bai

2009

IEEE Trans. Semicond. Manufact.

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The adsorption and desorption behaviors of ionic micro-contaminants on the silicon wafers in a cleanroom environment were investigated in this study. The experimental measurements showed that the surface density of ionic contaminants was significantly affected by both the exposure time and the properties of contaminants. The rate parameters of a kinetic model for surface deposition were determined by numerical optimization of fitting the experimental data on surface and ambient concentrations of airborne molecular contaminants (AMCs). Subsequently, the time-dependent deposition velocity and sticking coefficient of ionic species were obtained. The results showed that F , Cl , NO 3 , SO 2 4 , Na + , NH + 4 , K + , and Mg 2+ were the major ionic microcontamination species on the wafer surfaces, with the adsorption rate constant and the sticking coefficient of K + ion being larger than those of other ionic contaminants.After the determination of sticking coefficients, the allowable wafer exposure durations and the maximum ambient concentrations of ionic species were exemplified based on the guideline recommended by the International Technology Roadmap for Semiconductors (ITRS).

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Section: Surface Kinetics and Sticking Coefficientmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surface Deposition of Ionic Contaminants on Silicon Wafers in a Cleanroom Environment

Lin

Bai

2009

IEEE Trans. Semicond. Manufact.

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“…[10][11][12][13][14][15][16][17][18] For electrode surfaces, airborne molecular contamination introduces layer(s) of insulating organic matter through physisorption or chemisorption. In principal, the introduced organic contaminants act as energy barriers to the electrical transport through the interface formed with the electrode, and thereby affect the electrical behavior of the electrode and performance of the device.…”

Section: Introductionmentioning

confidence: 99%

EGaIn Microelectrode for Electrical Characterization of ITO-Based van der Waals Interface and Airborne Molecular Contamination of ITO Surface

Kong¹,

Yoon²

2015

J. Electrochem. Soc.

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This paper describes the electrical characterization of the van der Waals interfaces formed between indium-tin oxide (ITO) and a liquid metal-based microelectrode. We examined the influence of the adventitious contamination of the ITO surface by airborne molecular contaminants on the electrical transport across an ITO-based van der Waals interface. We constructed large-area junctions of the form ITO//Ga 2 O 3 /EGaIn, where EGaIn is a liquid eutectic gallium-indium alloy covered with a self-passivating thin oxide film (Ga 2 O 3 of ∼ 0.7 nm), and "//" denotes the van der Waals interface formed between the ITO and EGaIn electrodes. Comparisons of the current density data for junctions formed with ITO surfaces prepared via five different surface cleaning methods-utilizing UV light, ozone and/or organic solvent (ethanol)-indicated that the electrical conductance of the ITO//Ga 2 O 3 van der Waals interface was significantly enhanced (by three orders of magnitude) by UV/ozone surface cleaning, based on comparisons of the median value of the log-current density, and the dispersion of the data was significantly narrowed. The results reported in this work show that the electrical characterization of surfaces using the EGaIn-based microelectrode is an attractive method for investigating the electrical behavior of a conducting surface and the molecular adsorption phenomena on it.Thin films of indium-tin oxide (ITO) have received significant attention as optically transparent (∼90% transmittance in the visible wavelength range), electrically conducting (∼10 4 S/cm) electrodes in a variety of optoelectronic devices including solar cells, organic lightemitting devices (OLEDs), and liquid-crystal displays (LCDs). 1-5 In fabricating molecular and organic electronics with ITO thin-film electrodes, van der Waals (vdW) interfaces are often formed between the ITO surface and a molecular layer or another electrode. Understanding the electrical characteristics of such vdW interfaces and the influence of adventitious contamination on their properties is an important issue for improving the performance of molecular electronic devices. This information, however, remains elusive due to the experimental difficulties in generating vdW interfaces with high reproducibility and accessibility, and in measuring their electrical conductance in a statistically significant way, without the complexities that arise from a top-electrode such as ill-defined contacts and contact areas, airborne contamination on its surface, and the irreproducibility of its electrical behavior.This paper describes the formation and electrical characterization of junctions of the form ITO//Ga 2 O 3 /EGaIn, where EGaIn is eutectic gallium indium alloy that is covered with a self-passivating oxide film (Ga 2 O 3 of ∼0.7 nm), 6-9 and "//" denotes the vdW interface generated from the contact between the two electrodes. This type of junction allows the convenient generation of ITO-based vdW interfaces, their electrical characterization, and an examination of the relationship b...

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“…These contaminants can induce a variety of problems which are important in all types of semiconductor process. The air quality of a cleanroom environment must be tightly controlled to avoid yield reduction and performance deterioration of semiconductor devices (Kinkead et al, 1995;Kitajima and Shiramizu, 1997;Yeh et al, 2004;Chien et al, 2007). The monitoring and control of AMCs are major challenges for the present and future production of integrated circuit.…”

Section: Introductionmentioning

confidence: 99%

Metal Corrosion of Al-Si-Cu Pattern Wafer Due to Chloride Ion Contaminants

Bai

Lin

et al. 2012

Aerosol Air Qual. Res.

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Chloride ions (Cl -) induce metal corrosion of integrated circuits and cause wafer scrap events in the clean room environment. In this study, Al-Si-Cu pattern wafers were designed to monitor critical Cl -concentration which leads to metal corrosion effects in a simulated airborne molecular contamination (AMC) mini-environment. The simulated Cl -contamination was generated by HCl permeation tube in a mini-environment; meanwhile, the HCl concentrations in the mini-environment and the real fab were monitored by a real-time Ion Mobility Spectrometry (IMS) instrument. The exposed Al-1%Si-0.5%Cu pattern wafers were analyzed by the surface scanner, the optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analyzer. The critical HCl concentration where metal corrosion defects could be occurred and found on the wafer surface was around 2.9-4.7 ppbv for simulated minienvironment exposure within 1 hour, and 2.9-4.2 ppbv for real fab ambient air exposure within only 10 minutes. The results indicated that the Al-Si-Cu pattern wafer with TiW barrier layer is more sensitive than the Al-Cu pattern wafer with TiN barrier layer. It also proved that the permeation tube method can be served as a stable Cl -simulated source, which can control the simulated mini-environment to be within ~4% error in ppbv levels.

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The Removal of Airborne Molecular Contamination in Cleanroom Using PTFE and Chemical Filters

Cited by 29 publications

References 5 publications

Surface Deposition of Ionic Contaminants on Silicon Wafers in a Cleanroom Environment

Surface Deposition of Ionic Contaminants on Silicon Wafers in a Cleanroom Environment

EGaIn Microelectrode for Electrical Characterization of ITO-Based van der Waals Interface and Airborne Molecular Contamination of ITO Surface

Metal Corrosion of Al-Si-Cu Pattern Wafer Due to Chloride Ion Contaminants

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