Method and system for detecting phase defects in lithographic masks and semiconductor wafers

A scanning optical microscopy system configured to detect phase defects in a semiconductor processing photomask or wafer comprising:

• an optical beam generator to direct a light beam towards a surface of the semiconductor processing mask or wafer;
• a detector comprising at least four elements, wherein at least a first element and a second element of the at least four elements are used to generate respectively a first signal and a second signal, wherein the first element and the second element are selected to correspond to the orientation of opaque pattern lines on the photomask or wafer in the proximity of the first light beam location on the photomask or wafer;
• and
• an analyzer configured to obtain the difference between the first signal and the second signal to produce a resulting signal indicating whether there is a defect present.

A method for detecting phase defects in an inspected object during semiconductor processing, using an illumination imaging system, the method comprising:

• generating illumination from at least one source configured to illuminate the inspection object from at least 4 different directions;
• collecting the illumination corresponding to at least a first and second of the at least 4 different directions, wherein the illumination is reflected from or transmitted through the inspection object at a detector;
• and
• providing a differential signal from the collected illumination corresponding to the first direction and the collected illumination corresponding to the second direction.