A supercritical fluids is a high-pressure medium that possesses unique features such as solvent ability and nano penetration capability. Using supercritical carbon dioxide fluids as a medium for thin film deposition provides excellent gap-filling and step-coverage possibilities. This article describes firstly the principle and characteristics of Cu thin film deposition in supercritical carbon dioxide. The results on deposition kinetics study are then exhibited, and it is shown that Cu deposition proceeds via Langmuir-Hinshelwood mechanism. The capability of filling nanogaps for LSI interconnects and of coating high-aspect through silicon vias are demonstrated.
In this review, we discuss the synthesis of functional nanoparticles using supercritical fluids, focusing on their unique characters. Enhanced transport properties, larger solubility, and easy operation in changing the phase behavior realize the instantaneous formation of solid products, leading to the synthesis of fine nanoparticles with narrow size distribution. Several methods are shown to prepare organic and inorganic nanoparticles using supercritical carbon dioxide or water. We then introduce our recent activities on the supercritical hydrothermal synthesis of metal oxide nanoparticles whose surface is modified with organic molecules. The organic molecules change the surface chemical character of the metal oxide nanoparticles, facilitating their handling and hybridization. We hope that this review provides a guide to the synthesis of various nanoparticles that are used as a key component for functional materials and future nanodevices.
The organic reaction using supercritical water is not only harmonization with earth environment, it was also expected the compatible possibility of high reaction rate and high reaction controllability that was not obtained by the liquid phase reaction or gas phase reaction. However, the conventional supercritical water reaction system was not enough to elicit performance of supercritical water due to side reaction or excessive decomposition during heating process or cooling process. The micro reactor which was characterized by the high heat exchange rate and high mixing performance was applied to the supercritical water reaction system. The micro mixer for the quick heating and quenching was developed. As a result, the innovative organic reaction and inorganic reaction were developed.
For accurately controlling relativistic laser-plasma interactions to achieve repetitive proton generation, it is necessary to measure and control the laser irradiation conditions, such as laser parameters and target shooting accuracy, as well as to measure proton parameters for each laser shot. The displacement of the tape target, which is used in an ultra-short Ti: sapphire laser system to generate high-energy protons, is measured by capturing X-ray images of the laser plasma for each laser shot using an X-ray pinhole camera. This method allows the displacement of the target to be measured with a precision of 10 μm. The precision is high enough for present-day laser focusing systems with an F-number of 3.6 (f=179 mm). Thus, the proposed technique contributes to accurate control of repetitive laser-driven proton generation.