Investigation of the Airborne Molecular Contamination Behavior in 300 mm Semiconductor Front - End Manufacturing

Abstract

Front-end manufacturing of power semiconductor devices requires numerous different processes and materials. To control the complexity of fully automated 300 mm manufacturing lines, which typically utilize closed wafer containers, so called FOUPs (Front Opening Unified Pod), a systematic FOUP management concept is mandatory. This concept has to fulfill the quality targets in terms of organic and inorganic contaminants to assure the highest yield level of the semiconductor products. The focus of this study is to understand the behavior of airborne molecular contaminations (AMC) and to define strategies to prevent yield loss driven by AMC. The first step was to achieve a comprehensive knowledge of the AMC level within the different process steps of a selected power technology. Sampling and analysis procedures based on laser spectroscopy, measurements of electrical conductivity and mass spectrometry systems were used to understand the AMC level of the investigated components. A special automated research platform to analyze the gas phase in the FOUPs was used within the 300 mm high volume power semiconductor fab at Infineon Technologies Dresden. A pronounced dependence of the investigated component level on the different production steps was found. First offline root cause analyses due to contaminations of FOUPs with boron were performed using mass spectrometry, and the air filter systems used within the 300 mm cleanroom could be identified as a second source for boron contaminations. Other special experiments investigated the time dependency of the AMC level in the FOUP atmospheres. With this work, Infineon Dresden has established methods and strategies to prevent AMC-caused yield losses.