In this study, we focus on examining the stability of Al-based inorganic-organic hybrid thin films deposited through the molecular atomic layer deposition (MALD) process in ambient environment. Our observations reveal an initial reduction in material thickness within the first 3 days, followed by a period of stability. XPS analysis is employed to further investigate the chemical alternations in the aged Al-based hybrid thin films, revealing an increase in C=O species as well as overall oxygen content in the material. We also evaluate the effects of atmospheric exposure on the sensitivity of the Al-based hybrid thin films using electron flood exposure. This study aims to enhance the understanding of the stability of a vapor-phase synthesized hybrid thin film system for advanced resist applications.
Herein, we investigated the chemical reactions associated with low-energy electron exposures on an inorganic-organic hybrid thin film system deposited using molecular atomic layer deposition (MALD) for EUV photoresist applications. Using the hybrid thin films consisting of trimethylaluminum (TMA) and hydroquinone (HQ), we determined the critical doses and thickness contrast of the hybrid materials at various electron energies (up to 400 eV). The custom-built in-situ Fourier-Transform Infrared (FTIR) spectroscopy system, equipped with an electron flood gun and gas residual analyzer (RGA), was employed to monitor the chemical changes induced by low-energy electrons in the hybrid thin films. Based on the in-situ FTIR and RGA results, potential chemical reaction mechanisms responsible for the change in solubility of the TMA/HQ material are proposed.
Significant efforts have been dedicated to the development of inorganic-organic hybrid materials for next-generation EUV resists. Among the various synthesis, vapor-phase infiltration of metal source into existing e-beam photoresists using ALD process has drawn great attention. In this work, we have demonstrated the vapor-phase infiltration of both Hf and Al precursors into PMMA and HSQ resists, respectively. For example, under the electron exposure with 100 eV, both hybrid resists show relatively higher EUV absorption, increasing positive and negative tone. The detailed photochemical reactions of on electron exposure were investigated using an in-situ FTIR equipped with electron gun capability.
We report on the development of infrared sensor for monitoring of nitrogen as nitrate, nitrite and ammonia in municipal wastewater. To overcome the challenge of strong absorption of the infrared radiation in water, the radiation is transmitted through a waveguide in contact with water rather than through water itself, implementing an attenuated total reflection (ATR) mechanism. Infrared spectroscopy is a powerful tool for identification and quantification of functional molecular groups. Introduction of QCLs reduces the reliance on bulky Fourier Transform Infrared (FT-IR) spectrometers that are sensitive to vibrations and enables development of versatile, portable instrumentation. Efficient nitrogen removal is one of the key objectives of any municipal wastewater treatment operation, yet today, nitrogen is monitored through grab-sampling and sending samples to laboratories for analysis. The sensor will enable reliable, real-time, unsupervised sensing in harsh environment.
KEYWORDS: Thermography, Quantum cascade lasers, Near field scanning optical microscopy, Spatial resolution, Temperature metrology, Infrared imaging, Infrared radiation, Modulation, Near field
The fundamental optical diffraction in infrared microscopes limits their spatial resolution to about ~5μm and hinders the detailed observation of heat generation and dissipation behaviors in micrometer-sized optoelectronic and semiconductor devices, thus impeding the understanding of basic material properties, electrical shorts and structural defects at a micron and sub-micron scale. We report the recent development of a scanning near-field optical microscopy (SNOM) method for thermal imaging with subwavelength spatial resolution. The system implements infrared fiber-optic probes with subwavelength apertures at the apex of a tip for coupling to thermal radiation. Topographic imaging and tip-to-sample distance control are enabled by the implementation of a macroscopic aluminum tuning fork of centimeter size to support IR thermal macro-probes. The SNOM-on-a-fork system is developed as a capability primarily for the thermal profiling of MWIR quantum cascade lasers (QCLs) during pulsed and continuous wave (CW) operation, targeting QCL design optimization. Time-resolved thermal measurements with high spatial resolution will enable better understanding of thermal effects that can have a significant impact on a laser's optical performance and reliability, and furthermore, will serve as a tool to diagnose failure mechanisms.
Nitrate is a frequent water pollutant that results from human activities such as fertilizer over-application and agricultural runoff and improper disposal of human and animals waste. Excess levels of nitrate in watersheds can trigger harmful algal blooms (HABs) and biodiversity loss with consequences that affect the economy and pose a threat to human health. Municipal drinking water and wastewater treatment plants are therefore required to control nitrogen levels to ensure the safety of drinking water and the proper discharge of effluent. Nitrate exhibits distinct absorption bands in the infrared spectral range. While infrared radiation is strongly attenuated in water, implementation of fiber optic evanescent wave spectroscopy (FEWS) enables monitoring of water contaminants in real-time with high sensitivity. This work outlines the development of a non-dispersive infrared (NDIR) detector for the real-time monitoring of nitrate, nitrite and ammonia concentrations targeting implementation at municipal wastewater treatment plants (WWTPs) and onsite wastewater treatment systems (OWTS).
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