System and method of optically inspecting structures on an object

A method of inspecting a photoresist structure on a top surface of a semiconductor wafer die, said photoresist structure having a plurality of edges, the method comprising the steps of:

• shining a light on the wafer having the die thereon, said light illuminating the top surface of the wafer and the die so as to clearly expose the plurality of edges of the photoresist structure;
• capturing an image of a portion of the wafer having the die thereon;
• detecting a die image within the captured image;
• scanning the die image to detect the photoresist structure;
• tracing the photoresist structure to produce primitives for the plurality of edges of the photoresist structure, thereby producing a production grammar;
• and
• comparing the production grammar to a defect-free grammar representative of a defect-free die.

A method of inspecting a structure on a surface of a production object, said structure having a plurality of edges, said method comprising the steps of:

• emitting energy onto the surface of the object to illuminate the surface and the structure;
• capturing, with an image capturing device, a plurality of sequential images of the illuminated surface of the object and the structure;
• tracing the edges of the structure to generate primitives for each edge;
• creating a histogram for each of the plurality of images, the histogram identifying a slope and a length of each edge of the structure as captured in each of the images;
• aligning the images by aligning the histograms for the plurality of images;
• generating a production structure grammar from the aligned images;
• and
• comparing the production structure grammar with a reference structure grammar generated from a defect-free object to identify any defects on the production object.