Changhoon Oh

Spatially resolvable optical emission spectrometer for analyzing density uniformity of semiconductor process plasma

We proposed a spatially resolved optical emission spectrometer (SROES) for analyzing the uniformity of plasma density for semiconductor processes. To enhance the spatial resolution of the SROES, we constructed a SROES system using a series of lenses, apertures, and pinholes. We calculated the spatial resolution of the SROES for the variation of pinhole size, and our calculated results were in good agreement with the measured spatial variation of the constructed SROES. The performance of the SROES was also verified by detecting the correlation between the distribution of a fluorine radical in inductively coupled plasma etch process and the etch rate of a SiO(2) film on a silicon wafer.

Modeling and optimization of process parameters for GaAs/AlGaAs multiple quantum well avalanche photodiodes using genetic algorithms

In this paper, we present a parameter optimization technique for GaAs/AlGaAs multiple quantum well avalanche photodiodes used for the image capture mechanism in a high-definition system. Even under a flawless environment in a semiconductor manufacturing process, random variation in the process parameters can cause fluctuation in the device performance. The precise modeling for this variation is thus required for accurate prediction of device performance. This paper will first use experimental design and neural networks to model the nonlinear relationship between device process parameters and device performance parameters. The derived model is then put into genetic algorithms to acquire optimized device process parameters. From the optimized technique, we can predict device performance before high-volume manufacturing, and also increase production efficiency.

Nitrogen actinometry for measurement of nitrogen radical spatial distribution in large-area plasma-enhanced chemical vapor deposition

Density distributions of radicals in the large-area silicon nitride (Si3N4) plasma-enhanced chemical vapor deposition (PECVD) process were measured using a spatially resolvable optical emission spectrometer (SROES). To determine the qualitative distribution of a target radical, the authors used optical actinometry with nitrogen (N2) gas as an actinometer. To compare the SROES data and process results, the thickness of the deposited Si3N4 thin films using an ellipsometer was measured. By introducing nitrogen-based optical actinometry, the authors obtained very good agreement between the experimental results of the distributions of atomic nitrogen radical and the deposited thicknesses of Si3N4 thin films. Based on these experimental results, the uniformity of the process plasma in the PECVD process at different applied radio frequency powers was analyzed.

Modeling of octagonal spiral inductors for integrated circuit applications

As a need of embedded passive components is rising with the demand of small on-chip integrated circuit (IC) components, on-chip spiral inductor has become one of the key elements in IC designs according to S. Jenei et al. (2002). In this paper, modeling of octagonal spiral inductors with different number of turns is investigated.

Time-resolved absolute spectral analysis of IR countermeasure flares and its experimental validation by using an optical emission spectrometer with PbSe array detector

The absolute spectral radiant exitance of IR signatures from countermeasure flares for mid-IR was experimentally validated by using an optical emission spectrometer. A 256-array PbSe detector was installed to analyze the mid-IR emission spectrum of four IR signatures from countermeasure flares and propellants. We could evaluate the performance of the optical emission spectrometer and verify its usefulness in the field of IR countermeasures. The spectral response of the optical emission spectrometer was calibrated using a directly heated graphite blackbody; in addition, the total uncertainty was analyzed. The absolute amount of emissions of four IR signatures was calculated and compared.