Wavelength Stabilization in a Pulsed Light Source Using Optimal Control

Wednesday, November 14, 2018 - 4:00pm
3110 Etcheverry Hall
Kevin O'Brien

Senior Manager, Algorithms Group
Cymer Light Source


Cymer Light Source (an ASML Company) is the largest supplier of deep ultraviolet (DUV) light sources used by chipmakers to pattern advanced semiconductor chips or integrated circuits. To ensure the wafer exposure quality, the laser light must be controlled to have stable energy, wavelength and spectral bandwidth.


From a control system perspective, the light source is a multi-input-multi-output, nonlinear, and time-varying system. In this talk, we will focus on the wavelength control problem, where the challenges include unknown sample rate, measurement delay, various disturbances of known and unknown origins with frequency content beyond Nyquist frequency. A continuous-discrete Kalman filter was used for state estimation and a state feedback controller was found by solving a regularized minimum variance control problem under a disturbance rejection framework.


Kevin O’Brien is Senior Manager of the Algorithms Group at Cymer Light Source (an ASML Company). He received a Bachelor of Science degree in Mechanical Engineering from the University of California, Berkeley in 1994 and a Master of Science degree from the Massachusetts Institute of Technology in 1996, specializing in Controls and completing research on tele-robotics.


Kevin has enjoyed a successful career in industry. At Boeing, he developed control and estimation algorithms for spacecraft and advanced communications systems. At Cymer since 2006, he developed control algorithms for complex lasers used in leading edge microchip manufacturing and now leads a team of Controls experts to push the boundaries of achievable laser performance to enable and continue Moore’s Law. He holds 18 patents in areas such as spacecraft attitude control, estimation and navigation, communications systems, and a host of laser control technologies. He has co-authored several publications for lithography industry conferences.


Hosted by: Assistant Professor Koushil Sreenath, 5132 Etcheverry Hall, koushils@berkeley.edu & Assistant Professor Scott Moura, 625 Davis Hall, smoura@berkeley.edu