In this study, the phenomenon of particulate contamination of heated wafers contained in a closed environment like the front opening unified pod (FOUP), which is a fundamental component of minienvironment system in semiconductor manufacturing, was elucidated both experimentally and numerically. The degree of particulate contamination of heated wafers was examined according to the position of the wafers in the closed environment. The results showed that particles, if any, generated inside the closed environment such as the FOUP could be carried by natural convection flow and deposit on the heated wafer placed at the upper position in the closed environment. As a result, the topmost wafer was the most vulnerable to particulate contamination. The effect of the wafer temperature on the degree of particulate contamination of the topmost wafer was investigated, and a narrower contaminated area appeared at a higher wafer temperature condition. (C) 2015 Elsevier Ltd. All rights reserved.