Prevention of Moisture Invasion by Flow Isolation Device (FID) for Mask Automatic Storage System (Stocker Room) in a Semiconductor Fabrication Plant (Fab)

Abstract

recent developments in semiconductor manufacturing have seen feature sizes reduce to as small as 3 nm. It is predicted that 2 nm, or even 1 nanometer will be achieved soon. Improving the level of cleanliness of the wafer mask during manufacturing can lead to improved product yield and quality. The quality of lithography technology and the reticle is one of the most important items in the wafer manufacturing process. The cleanliness of this process directly affects the wafer quality and yield. Because the wafer manufacturing process involves the stacking of multiple reticles through lithography technology, semiconductor factories mostly use a reticle stocker room to store the photomasks. However, the reticle is susceptible to defects caused by moisture, particles, and molecular contaminants in the air. Therefore, the reticle stocker room environment requires high cleanliness and humidity control. In this study, the flow stream lines, velocity and humidity fields associated with a flow isolation device (FID) installed in a reticle stocker room were analyzed with the assistance of computational fluid dynamics (CFD) software developed by ANSYS Fluent. Different velocity (V=1 m/s, 1.5 m/s, 2 m/s) of the flow isolation device were examined. The results show that under the same velocity (V=1 m/s), the wider the outlet width of the flow isolation device (W ${=}0$ .2 m), the higher the isolation efficiency ( $\eta {=}83.9$ %). The results also show that the faster the velocity of the flow isolation device (V =2 m/s), the better the isolation efficiency ( $\eta {=}88.2$ %) under the same outlet width (W ${=}0$ .1 m). The use of the flow isolation device can effectively reduce the supply of clean dry air (CDA) by up to 40%, greatly reducing energy consumption during semiconductor manufacturing. According to the results of this study, when using both a hollow fiber adsorption dryer and a flow isolation device with a width of 0.1 m and an outlet wind speed of 2 m/s, it can save 118,514 kWh per year, and its energy saving rate is 92.03%.