| 摘要 |
PURPOSE:To obtain a best focus position by a simple constitution of device in a short measurement time in a highly precise manner by a method wherein rediffracted beams which is generated at angles different with each other and obtained by making diffracted lights of different angle with each other is incident on a lattice pattern, are detected by the detector provided on an almost conjugated surface of an optical system. CONSTITUTION:At least two diffracted beams of U(-1), U(0) and U(epsilon+1), which are generated at different angle with one another, are made incident on a projection optical system by projecting a first pattern on a first object at the periodic structure of the prescribed pitch. When the above-mentioned diffracted beams are projected on the second pattern which is formed on a second object in the same direction in the periodic structure of the prescribed pitch, at least the two rediffracted beams {U'(-1), U'(0) and U'(epsilon+1)} generated by rediffraction are received on the surface which is almost conjugated with the pupil surface of the projection optical system, and a plurality of adaptable signals are outputted. The second pattern and the diffracted beams are relatively shifted, the relative phase difference between signals is detected by the plurality of signals which are outputted after modulation by the prescribed amplitude by the above-mentioned relative movement, and the amount of deviation from the conjugated position of the first object and the above-mentioned second object is worked out. |
