Abstract

An apparatus for accurately positioning a laser beam on a semiconductor surface, for example for repairing an integrated circuit, has a translational beam positioning apparatus and a galvanometer based beam positioning apparatus. The translational beam positioning apparatus has first and second platform members, the second platform member moving relative to the first platform member and supporting the galvanometer system. The galvanometer beam positioning system thus moves with the second platform member to cover the surface of an integrated circuit on which "repair" is to be performed. The second platform member further supports an optical system positioned relative to the galvanometer beam positioning system so that a small and uniform spot size can be achieved, at high speed, using small galvanometer mirrors. Thereby, the galvanometer beam positioning system provides high speed movement of a laser beam over a relatively small area and the translational system provides broad, highly accurate, but slower movement of the entire system across the entire integrated circuit. A method for calibrating the galvanometer system employs apparatus for measuring the exact position of the translational system. A comparison of feature measurements using both the translational system and the galvanometer system enables accurate and reliable calibration of the galvanometer system.

Other References

• Fisher et al., Teradyne, "Laser Trimming of Monolithic Analog LSI Devices", 1980
• "A 330 Teradyne Monolithic Trim System", 1981