ABSTRACT
Wafer fabrication facilities (referred to as “fabs” throughout this book) are generally constructed with a few levels, with the main two levels being the fab level and the subfab level (the level below the fab). The fab level has the wafer processing equipment. The subfab (and any subfloors and other spaces) has exhaust ductwork, wastewater drains, chemical piping, gas piping, process support equipment, etc. This subfab space can be fairly congested. In older fabs, chases are used. Chases are on the same level as the wafer process equipment and contain some of the same equipment as the subfab. Some wafer fabs have both chases and subfab. It is important when understanding the exhaust management of the fab to review its design and where the exhaust ductwork is located. For example, some fabs have exhaust ductwork below the process equipment, and some fabs have the ductwork above the process equipment; many fabs have both.
