| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an overlay system capable of recognizing overlay error, being larger than the pitch of an overlay marker lattice, relating to alignment of a projection exposure. <P>SOLUTION: The overlay target on a substrate comprises two pairs of lattices. A first pair has a pitch P1, and a second pair has a pitch P2, with each pair containing a lattice oriented almost vertical to the first lattice. When a resist layer is aligned with a layer below it, the same overlay mark is provided on the upper layer. The relative positions of the overlay targets on the upper and lower layers are compared each other by measuring diffraction spectrum after overlay beam is radiated on the overlay targets. By providing two pairs of overlay targets having different pitches in each lattice, such overlay error which is larger than either one pitch in the overlay lattice can be measured. <P>COPYRIGHT: (C)2008,JPO&INPIT |
