Solving Semiconductor Equipment Leveling Problems and Establishing Process Uniformity Standards

摘要

In order for semiconductor process equipment to operate efficiently, very precise leveling standards are needed for all wafer process and transfer locations. However, when asked about the leveling standard at their fab, most process or equipment maintenance engineers responded, "We have no leveling standards." It is inherently difficult to measure the inclination of semiconductor process equipment as access to the equipment may be limited and traditional leveling methods, including eyeballing and bubble levels, do not have the precision or repeatability required to establish leveling standards. The risks of insufficient inclination measurement and non-conformity across the wafer production process include: (1) Wafer damage -- as a result of vibration, slippage, or scratching (2) Particle contamination (3) Increased equipment downtime (4) Increased maintenance burden (5) Wafer non-uniformity (6) Process nonconformity (7) Increased defects and reduced yield. This paper describes case studies illuminating the challenges and limitations of current leveling methods and the experience of one maintenance team in a Korean fab using a new inclination measurement technique, a wireless, leveling wafer that can be handled by the automation and moved anywhere throughout the equipment.