Japanese journal of applied physics part 1-regular papers short notes & review papers vol:31 issue:8 pages:2631-2639
A quantitative description of the optical performance of a pre-objective scan system for the laser recrystallization of silicon on insulator (SOI) material is given. The thermal effects induced by the high power argon-ion laser beam in the transmitting optical components making up the optical path of the laser beam are discussed extensively. Thermal lensing in plan-parallel optics and heating of the flat field scan lens by the laser beam leads to a recrystallization condition dependent beam waist position of the focused laser beam. A model is presented to calculate the beam waist position as a function of the recrystallization parameters. Using this model it is possible to predict the thermal defocusing and compensate for it by adjusting the wafer position. in this way a recrystallization parameter independent spot size can be obtained on the wafer. A critical evaluation of the pre-objective scan technique is given.