A study of air molecular contamination (AMC) and volatile organic compounds (VOC) in new AMC/VOC controlled cleanroom

• Main Author: Wong, Chee Kong
• Other Authors: Zhong Zhaowei
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/136645
• Institution: Nanyang Technological University

Airborne Molecular Contaminants (AMC) may cause different flaws on an electronic device [1]. It is especially so in the semiconductor manufacturing sector. Monitoring of AMC is becoming essential when it comes to managing cleanroom for the present production of semiconductor devices as it advances into DUV and EUV range of manufacturing processes. For this requirement, a new ISO 5 (Class 100) AMC/VOC controlled cleanroom was built with the stringent controlled condition of VOCs of RT>RT toluene, siloxanes and TVOC which is essential to the new advance products to be manufactured in the company premise. The new cleanroom will be the focus study of this project by studying the VOCs produced and gradually reducing them at each phase of the cleanroom build. Air samples were taken at each stage of airflow in the filtration system from intake environment, MAU, before the cleanroom (at FFU) and at the production cleanroom itself. The air samples collected were tested and analysed by the Gas Chromatography-Mass Spectrometry / Thermal Desorption method. The required VOC specifications of the new cleanroom were met based on test results from 1 to 4. Test results from 5 to 8 are to suggest a maintenance regime that will be essential to keep required VOC within the required specifications in the cleanroom production area. The test data showed that the external environment contributes to the VOC count in the cleanroom. The air quality of the surrounding environment is very vital to the design of the filtration system setup, and it affects the type of chemical filters used. The air intake has to be adequately filtered so that the subsequent stages of VOC filtration is performing effectively and making sure that the cleanroom environment is within the VOC specifications for the cleanroom and the product. Based on results, the cleanroom had met the required condition after the 4th test result. The final performance of three targeted VOCs specifications of RT>RT Toluene < 2 µg/m³, Siloxanes < 0.1 µg/m³ and TVOC < 5 µg/m in the cleanroom were within the designed requirement. From results of test 5 to 8, conclusion for the best maintenance regime to maintain the specifications was to replace the chemical filter every two weeks at the MAU to prolong the time of the FFU until the next service in one years' time. Replacing chemical filters is costly. Thus, further study needs to be done to keep the operating cost low.