Patent ID: 7193715
Filing Date: 2007-03-20
Classification: G01N,G03F

Abstract:
1. A method for optically inspecting and evaluating a sample fabricated with lithography process, the method comprising: projecting a probe beam at an overlay metrology target included in the sample, where the overlay metrology target includes one or more gratings built into an upper layer of the sample, each of which is paired with a respective grating built into a lower layer of the sample; analyzing the diffraction imparted to the probe beam by the gratings of the overlay target to measure fine overlay between the upper and lower layers; measuring the overlay metrology target by optical microscopy to determine the gross overlay between the upper layer and the lower layer of the sample; generating a total overlay measurement that is consistent with both the fine and gross overlay measurements; and using the total overlay measurement to control the lithography process.