Method For Measuring The Position Of A Mark In A Deflector System

Abstract

The present invention relates to a method for determining the coordinates of an arbitrarily shaped pattern in a deflector system. The method basically comprises the steps of: moving the pattern in a first direction (X), calculating the position of the edge of the pattern by counting the number of micro sweeps, performed in a perpendicular direction (Y), until the edge is detected, and determining the coordinates by relating the number of counted micro sweeps to the speed of the movement of the pattern. The invention also relates to software implementing the method.

1 . A method of deriving boundary locations of edges of an arbitrarily shaped pattern on a microlithographic surface, including:
 deriving each boundary location from multiple measured boundary transitions of a beam swept across one or more edges of an arbitrarily shaped pattern, wherein the multiple transitions are measured in multiple beam sweeps with a measurement clock that has a pseudo random phase relationship to a sweep clock;   whereby the derived boundary locations of the edges on are mapped in two dimensions of space to a microlithographic surface with greater precision than could be achieved by measuring at a sampling frequency of either the sweep clock or the measurement clock.   
     
     
         2 . The method of  claim 1 , wherein
 the beam is swept in a first direction, synchronized to the sweep clock, which operates at a first frequency;   the measurement clock operates at a second frequency, producing measurement clock pulses that are pseudo randomly related in time to the sweep clock; and   the swept beam is moved relative to the arbitrary shaped pattern on the surface in a second direction.   
     
     
         3 . The method of  claim 2 , wherein the first and second directions are generally perpendicular.