EUV Lithography Pre-Pulse Beam Alignment With Dual Feedback

The patent implements a feedback control system using a quad-cell sensor to detect the actual position of the pre-pulse laser beam and a camera sensor to monitor droplet position. The controller receives signals from both sensors and dynamically adjusts the pre-pulse laser beam position to maintain accurate alignment with the disc-shaped target, thereby resolving the position accuracy issue while preserving the efficiency benefits of pre-pulse deformation.

The patent replaces mechanical alignment adjustment mechanisms with an optical sensing and control system. Instead of physically adjusting the laser beam path through mechanical components, the system uses optical sensors (quad-cell sensor and camera sensor) to detect positions and employs electronic control to steer the laser beam, achieving higher precision and dynamic adaptability.

The dual-feedback control system continuously monitors both the pre-pulse laser beam position (via quad-cell sensor) and droplet position (via camera sensor), and dynamically adjusts the beam alignment in real-time. This feedback mechanism ensures consistent EUV radiation dosing by compensating for position variations without requiring complex mechanical adjustment systems, thus maintaining both speed and reliability.

The control system performs multiple functions simultaneously: it detects beam position, detects droplet position, calculates alignment errors, and adjusts the laser beam steering. This multi-functional approach consolidates what would otherwise require multiple separate systems into a single integrated control unit, achieving reliable dose consistency without increasing system complexity or reducing alignment speed.