Chucking sensor using floating esc power supplies

Abstract

Electrostatic chucks (ESCs) are used to provide a clamping force between the substrate and the pedestal during semiconductor processes. However, it is difficult to measure a chucking state of the substrate during a live process, as this usually requires invasive measurements or additional hardware to be added to the pedestal. A new technique for monitoring a chucking state electrically isolates the ESC from the system ground to create a single conductive path through the ESC power supplies, ESC electrodes, and the substrate. A floating voltage between the two power supplies may change with the chucking state of the substrate, and this voltage may be monitored to determine the real-time chucking state of the substrate. This provides an unintrusive way to monitor the ESC state in real-time during a semiconductor process at the controller without disturbing the process or modifying the pedestal.