f-theta lens design.

Laser annealing is growing rapidly in the semicon market. The elementary module for the laser annealing process is a laser beam delivery system that conditions the laser beam such that a uniform annealing is achieved over the surface. Demcon focal developed a laser annealing module in cooperation with a partnering system integrator.

Our contribution:
● The development of a custom-made F-theta lens with a long working distance
● Reduction of angular displacement errors due to manufacturing tolerances
● Tooling design and development for optical alignment and qualification

Project specifics


● Focal length of 280mm
● Scan range of 7mm with ± 4 degree (Gaussian) input beams
● 500W laser with wavelength of 500 nm
● F-theta distortion less then 0.01%
● Useable DOF ~ 1 um
● Distortion < 100nm (maximum over field)


● Magnification needs to be adjustable using back-focus
– Order of magnitude 10 ppm
● Minimize magnification and focus errors due to short term temperature fluctuations within +/-0.1 degree
● Magnification chang and focus due to pressure change is compensated using focus and back-focus only