Patent ID: 6417922
Filing Date: 2002-07-09
Classification: G03F,H01L

Abstract:
An alignment device constructed and arranged to align a first object which is provided with at least one first alignment mark, with respect to a second object which is provided with at least one second alignment mark, said alignment device comprising:a radiation source constructed and arranged to supply an alignment beam irradiating one of said first and second alignment marks, a first object holder constructed and arranged to hold said first object, a second object holder constructed and arranged to hold said second object, an alignment imaging system arranged between said first alignment mark and said second alignment mark, said alignment imaging system imaging one of said first and second alignment marks onto the other alignment mark by the alignment beam for a purpose of alignment control, and a detection system sensitive to the alignment beam radiation and arranged in the path of alignment beam radiation coming from said other alignment mark, said detection system converting alignment radiation into an electrical output signal, wherein the first and second alignment marks are periodic structures which deflect the alignment beam into several diffraction orders sub-beams, the detection system detecting only selected sub-beams and the output signal of the detection system being indicative of the extent to which the first and second object are aligned with respect to each other, wherein the wavelength of the alignment beam is between about 980 nm and 1100 nm.