| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 103 === In this study, an innovative stroboscopic moiré measurement technique (SMMT) for real-time warpage measurement in the process of metal organic chemical-vapor deposition (MOCVD) is developed. The proposed SMMT is developed by combining the design concepts of stroboscopic technique,moiré shift method, digital moiré method, scanning profile method, and autocollimator. High measurement resolution and high system stability can be achieved.
The system configuration of our proposed SMMT is simple and can be carried out wasily. It consists of a LED light source, a linear grating, focusing lenses, a Charge-coupled Device (CCD) camera, and a data acquisition (DAQ) card.The image of a linear grating is projected onto a wafer surface and then reflected into the CCD camera to obtain the image of the measurement grating. By overlapping the images of the measuring grating and the reference grating (physical or digital), a corresponding Moiré fringe is formed. When wafer warpage occurs, the phase of the moiré fringe will be changed proportionally. By integrating the techniques of stroboscopic and scanning profile, the wafer warpage and contours can be obtained by analyzing the phase shift of the moiré fringes in each according detection region of the wafer surface along radial direction.
The experimental results demonstrate that the proposed measurement technique can precisely measure wafer warpage in the situation of high rotation speed. The measurement resolution is able to achieve 0.21µrad. Moreover, the proposed SMMT can beo mounted on a MOCVD reactor chamber without affecting the process quality of epitaxy. As compared with current warpage measurement techniques of the single beam, double beams, interferometer, shadow moiré, or reflection moiré, the proposed SMMT has the merits of high resolution, high sensitivity, and high flexibility.
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