Enhancing Lithography Process Control Through Advanced, On-Board Beam Parameter Metrology For Wafer Level Monitoring Of Light Source Parameters

In order to improve process control of the lithography process, enhanced On-board metrology, measuring of the light source beam parameters with software solutions for monitoring, reporting and analyzing the light source's performance has been introduced.Multiple lasers in the field were monitored after installing of a new On-board metrology product called SmartPulse. It was found that changes in beam parameters can be significantly reduced at major module change service events when new service procedures and On-board metrology were used, while significant beam parameter shift and illumination pupil changes were observed when On-board metrology was not available at service events, causing lengthy scanner illumination pupil recalibration.SmartPulse (TM) software from Cymer Inc. was used to monitor the variation of light source performance parameters, including critical beam parameters, at wafer level resolution. Wafer CD was correlated to the recorded beam parameters for about a month of operation, and both wafer CD and beam parameters showed stable performance when the light source was operating at optimal conditions.