Papers by Author: Kang Ho Ahn

Abstract: A feasibility test for real-time fine particle measurements in vacuum semiconductor processing equipment has been conducted. The approach in monitoring particles in process equipment is an installation of a sensor at a critical location inside the process equipment (hence the term ‘in-situ’) to track free particle levels in real-time. Common method for particle detection in a process chamber today is a use of test wafer with a laser wafer scanner. However, this method does not give a real time information of the particle status in the process chamber. In this paper, a new method has been developed to detect particles in real time in vacuum system for particles smaller than an optical method can detect. The system consists of a particle charging region and a particle detection region in a vacuum system. Particles with 50nm are successfully detected at about 10 torr region.

Abstract: Fe2O3 nano-particles coated with SiO2 are synthesized using H2/O2 co-axial diffusion flame with the state-of-the-art electro-spraying (e-spray) technique at atmospheric condition. Fe(CO)5 and TEOS (tetra-ethyl-ortho-silicate) mixture in liquid phase is injected directly into the center of the flame using the electro-spraying method. The synthesized particle characteristics are analyzed with HRTEM, XRD, SQUID. The core (iron oxide)-shell(silica) structured spherical particles are obtained. Most of the particles synthesized are magemite(
) regardless of the particles sampling positions inside the flame.

Abstract: Ultra-fine Fe2O3 nano-particles are synthesized using H2/O2 co-axial diffusion flame with the state-of-the-art electro-spraying (e-spray) technique at atmospheric condition. Fe(CO)5 is used as a precursor and the liquid phase Fe(CO)5 is injected directly into the center of the flame using the electro-spraying method. The synthesized particle morphology sampled from the inside of flame is analyzed by TEM. The synthesized particles showed different crystal structures for different particle collection method and the collection positions.