Substrate alignment detection using circumferentially extending timing pattern

Abstract

Apparatus and method for aligning a rotatable substrate to a support mechanism such as a turntable. The substrate has a circumferentially extending timing pattern comprising at least spaced apart first and second timing marks disposed on opposing sides of a center point of the substrate. The substrate is configured to be mounted to and rotated by the support mechanism about a central axis. The center point of the substrate may be offset from the central axis by an offset distance due to mechanical tolerances associated with the substrate mounting operation. The offset distance may be determined through successive detection of the first and second timing marks by a detector over at least one rotation of the support mechanism and the substrate. A write beam may be adjusted using the determined offset distance to write a second feature to the substrate in alignment with a previously written first feature.