Optical inspection method and apparatus having an enhanced height sensitivity region and roughness filtering

An optical inspection system for inspecting a surface under inspection, said inspection system comprising:

• an optical illumination system for producing a beam for illuminating a surface under inspection;
• a detector for measuring an optical signal from light reflected from said surface under inspection;
• means for increasing an optical signal generated by light reflected from defects on said surface under inspection that exceed a predetermined height;
• and
• a scanning system for moving said beam across said surface under inspection.

An optical inspection system for inspecting a surface under inspection, said inspection system comprising:

• an optical illumination system for producing a beam for illuminating a surface under inspection;
• a detector for measuring an optical signal from light reflected from said surface under inspection;
• means for decreasing an optical signal generated by light reflected from defects on said surface under inspection that do not exceed a predetermined height;
• and
• a scanning system for moving said beam across said surface under inspection.

A method for inspecting a surface under inspection, said method comprising:

• illuminating a partially reflective surface with an illumination beam from an illumination subsystem;
• illuminating said surface under inspection with a transmitted beam that is transmitted from said illumination beam through said partially reflective surface, wherein said partially reflective surface and said surface under inspection are positioned substantially parallel to each other and at a tuned optical distance such that a reflected beam reflected from defects on said surface under inspection that exceed a predetermined height has an increased signal sensitivity;
• positioning said beam at a location on said surface under inspection;
• and
• detecting said reflected beam from said defects.