Defect detection system and method for pattern to be inspected utilizing multiple-focus image signals

A defect detection method for a circuit pattern to be inspected which a circuit pattern is processed in a plurality of stages in respective processing devices, comprising the steps of:

• performing inspection on the circuit pattern to be inspected before and after processing of the circuit pattern in a respective processing device by inspecting for at least two of a foreign matter defect, a discoloration defect and a deformation defect;
• determining whether a defect occurs in a same position on the circuit pattern to be inspected before and after processing in the processing device;
• and
• classifying the defect as a fatal defect of the circuit pattern to be inspected, by detecting that the defect inspected as the foreign matter defect before processing in the processing device is detected upon inspection to be one of the discoloration defect and the deformation defect after processing in the processing device.

A defect detection system for a circuit pattern to be inspected comprising:

• means for obtaining multiple-focus image signals of the circuit pattern to be inspected by imaging with at least an image pickup means at different focal positions of the circuit pattern;
• means for aligning at least one image signal of the multiple-focus image signals of the circuit pattern to be inspected with at least a corresponding one image signal of multiple-focus image signals of a reference circuit pattern;
• and
• means for detecting a foreign matter defect of the circuit pattern so as to discriminate from a discoloration defect and a deformation defect on the circuit pattern in accordance with a density value of a difference image signal obtained by comparing with a comparing means at least the aligned one image signal of the multiple-focus image signals of the circuit pattern and the reference circuit pattern.

A defect detection system for a circuit pattern to be inspected which a circuit pattern is processed in a plurality of stages in respective processing devices, comprising:

• means for performing inspection on the circuit pattern to be inspected before and after processing of the circuit pattern in a respective processing device by inspecting for at least two of a foreign matter defect, a discoloration defect and a deformation defect;
• means for determining whether a defect occurs in a same position on the circuit pattern to be inspected before and after processing in the processing device;
• and
• means for classifying the defect as a fatal defect of the circuit pattern to be inspected by detecting that the defect inspected as the foreign matter defect before processing in the processing device is detected to be one of the discoloration defect and the deformation defect after processing in the processing device.