HIGH-RESOLUTION, HIGH-SPEED, LOW DATA AGE UNCERTAINTY, HETERODYNE DISPLACEMENT MEASURING INTERFEROMETER ELECTRONICS

An advanced displacement measuring interferometer system has been deve loped to satisfy the needs of semiconductor manufacturing and lithogra phy. The system electronics provides a position resolution of 0.31 nm at velocities up to 2.1 m s(-1) when the system is used with a double- pass interferometer. Output data rates up to 10(7) samples per second are available. The data age, which is the delay from the interferomete r optics to the measurement sample, can be adjusted to equalize differ ences between axes to within 1 ns. This low data age uncertainty is ne cessary for high-resolution, high-speed, multiple-axis measurements.