| Summary: | 碩士 === 國立中央大學 === 光機電工程研究所 === 104 === An in-situ monitoring system for Metal Organic Chemical Vapor Deposition (MOCVD) process is presented. The proposed monitoring system consisted of the modules of growth-rate and temperature, which is able to precisely measure the growth rate of thin film and the surface temperature of wafer in the MOCVD process. The principles of monitoring system are based on the thin film interference theorem and the blackbody radiation. In our system, the detector received the reflectance variation of thin film and the thermal radiation of wafer, while a lock-in amplifier was used to demodulate the reflected light of laser source and the thermal radiation signal. According to the thin film interference theorem and Kirchhoff’s law, the thin film growth rate and compensated temperature can be obtained.
To demonstrate the feasibility of the growth-rate module, we designed an air layer that can change its thickness by using a piezoelectric (PZT) actuator. We also implemented the photoresist spin coating on a silicon wafer experiment to verify the measurement ability. To demonstrate the feasibility of the temperature measurement module, the 940 nm and 400 nm band of the thermal radiation resulting from the surface of the heated silicon wafer was received by the temperature module and used to determine the surface temperature of the wafer.
The experimental results demonstrate that the growth rate, optical constants of the film, and temperature of wafer surface could be precisely determined in real time. Comparing the measurement results obtained using our proposed system with the ones obtained by the commercial metrology equipment (surface profiler and pyrometer), the relative differences are less than 2%.
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