Use In Semiconductor Manufacturing Research Articles

Analysis of Plasma and Gas Characteristics According to the Recovery Process Using a New Alternative Gas

Perfluorocarbon (PFC) gas, which is predominantly used in the etching and chamber cleaning processes of semiconductor manufacturing, is very stable and remains on Earth for long periods. Moreover, it has a high global warming potential because it blocks the emission of radiant heat from the Earth and contributes to global warming. To mitigate these effects, the waste PFC gas can be recovered and reused, which also limits the unnecessary waste of resources. In this study, the liquid fluorocarbon C6F6, which has a high C/F ratio and exists as a liquid at room temperature, was selected as an alternative to PFC gas, and adsorption and recovery were performed through an adsorption module during the plasma process. To characterize the recovered gas, residual gas analysis was performed on the gases recovered during etching. In addition, optical emission spectroscopy and printed circuit board probes were used to characterize the plasma. Finally, the feasi-bility of the gas recovery process was evaluated by comparing the thicknesses of the CF polymers produced in Si and SiO2 using an ellipsometer. The results revealed that the C6F6 had similar characteristics before and after recovery, confirming that this gas can be reused and is suitable for use in semiconductor manufacturing as a green alternative.

A Study on the Moving of an AC Attraction-type Magnetic Levitation Transport System Using a Two-phase Linear Motor

Magnetic Levitation Transport system is suspended by magnetic levitation, and it is therefore basically free of contact parts that produce dust particles by friction. In order to take advantage of this no-dust characteristic, a number of magnetic levitation systems are currently being developed as transport systems for use in semiconductor manufacturing processes.The authors proposed the development of a new magnetic levitation system using a linear induction motor. Although the magnetic levitation characteristic was stabilized successfully, the moving control was complicated because the moving speed is dependent on the frequency of the commercial-frequency power supply. The present paper proposes the moving control of an AC attraction-type magnetic levitation transport system using a two-phase linear motor. The present system uses a low-frequency two-phase sinusoidal power supply amplitude-modulated from the commercial-frequency power supply. The levitation force is generated and controlled by a commercial-frequency AC magnetic field. In order to control the moving of the system, a low-modulation frequency control method is adopted.

Semiconductor and thin film applications of a quadrupole mass spectrometer

Commercial quadrupole mass spectrometer (QMS) residual gas analyzers became available in the late 1960s and have been popular in R&D laboratories, but have found limited use in semiconductor manufacturing. To sample at pressures above 10−5 Torr with ppm sensitivity or better (relative to the total process pressure), differential pumping is usually required. The newly available, small, high-pressure QMS sensors can operate as high as 10–20 mTorr without differential pumping, but provide somewhat lower mass resolution and partial pressure sensitivity than a standard QMS. Applications in semiconductor manufacturing include equipment monitoring, process monitoring, and effluent analysis. Equipment monitoring can include qualification after preventative maintenance, rate-of-rise tests, and leak identification and detection. Usually the burning question is, Why won’t the vacuum chamber pump down? Other uses that are not usually considered include the qualification of replaceable parts: sputter cathodes, electrodes, lamps, shields, etc. In process monitoring, the key question is, Is this process running normally? A manufacturing monitor can be useful simply by providing a comparison between a well-behaved high-yield process and a marginal or failing process. Examples are given for physical vapor deposition (sputtering) processes, chemical vapor deposition, and plasma etching. The effluent from chemical vapor deposition and plasma etch processes can be analyzed to measure the efficiency of process gas utilization or to monitor the efficacy of abatement methods used for the removal of global warming gases.

Development of a stainless steel tube resistant to corrosive Cl2 gas for use in semiconductor manufacturing

In order to develop a corrosion-free halogen gas delivery system for use in semiconductor manufacturing, Cr2O3 passivation of ferritic and austenitic stainless steels has been investigated. It has been shown that a Cr2O3 layer can be formed on an electropolished (EP) surface of ferritic 26Cr–1Mo stainless steel by oxidation above 600 °C, but excellent corrosion resistance performance to Cl2 gas can be obtained only by oxidation above 700 °C. On the other hand, on the EP surface of austenitic SUS 316L, a corrosion-resistant Cr2O3 layer is not formed by oxidation even up to 800 °C.

Real-Time Implementation of a Robust H∞ Controller for a 2-DOF Magnetic Micro-Levitation Positioner

Robust H∞ optimal control theory has proven to be one of the best techniques in linear control system design. The achievable robust stability and performance are high, but the resulting controllers are very complex and difficult to implement. As a result, few practical implementations of H∞ control can be found in the literature. This paper presents a robust H∞ controller for a two-degree-of-freedom magnetic micro-levitation positioner and its real time experimental implementation. The experimental device used in this study is designed for use in semiconductor manufacturing and consists of two U-shaped electromagnets and a manipulator. First, we describe the system dynamics in state space form. Second, the system which is unstable in nature is stabilized using the H∞ synthesis. The H∞ control design problem is described and formulated in the standard form with emphasis on the selection of weighting transfer functions that reflect robustness and performance goals. The interactive computing environment MATLAB is used to calculate the controller. Third, the controller is implemented digitally using a digital signal processor with 16 bit A/D and 12 bit D/A converters. Finally, some simulation and experimental results are presented. The results obtained show that robust stability against model uncertainties is achieved and the performance goals are satisfied.