Mark detecting method and apparatus

DETAILED DESCRIPTION According to the above-identified proposal, however, the search has to be made while moving the wafer stage in a blind-feeding manner.
Therefore, there is a good possibility that the time for the search is prolonged with a disadvantageous result of reducing the throughput with regard to the mark detection.
It is accordingly an object of the present invention to, in a system for detecting a predetermined mark provided on an object, reduce in time for the search of the mark as well as to improve the throughput.
In order to achieve this object, in one aspect the present invention provides a mark detecting method and apparatus wherein a first mark comprising a first particular pattern and a group of second marks each comprising a second particular pattern and bearing positional information indicative of the positional relationship between it and the first mark, are preparatorily formed on an object.
For detection of the first mark by using an image pickup means, when any one of the second marks is detected, the positional information that the detected second mark bears is used, such that on the basis of the positional information the first mark is detected.
With this structure, detection of any one of second marks (provided on an object) through an image pickup means simply results in detection of such information that the detected second mark bears and that is indicative of the positional relationship between the first mark and the detected second mark.
On the basis of the detected positional information, the location of the first mark can be easily detected.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.