Definition of alignment

1 : the accuracy of the relative position of an image on a reticle with reference to an existing image on a substrate. [SEMATECH] 2 : a procedure in which a wafer is correctly positioned relative to a reticle. [SEMATECH] 3 : the mechanical positioning of reference points on a wafer or flat panel display substrate (also called alignment marks or alignment targets) to the corresponding points on the reticle or reticles. The measure of alignment is the overlay at the positions on the wafer or substrate where the alignment marks are placed. [Adapted from SEMI P18-92 and D8-94] Also see direct alignment and indirect alignment .